The Ahlulbayt are the fulfilment of Allah swt's covenant with Ibrahim (as)
Quran 3:33-34: Allah swt chose Adam, Nuh, the family of Ibrahim, and the family of Imran above all people.
Quran: Ali 'Imran 3:33-34
Translation: Abdullah Yusuf Ali

33: Allah did choose Adam and Noah, the family of Abraham, and the family of 'Imran above all people,

 

34: Offspring, one of the other: And Allah heareth and knoweth all things.

إِنَّ ٱللَّهَ ٱصۡطَفَىٰۤ ءَادَمَ وَنُوحࣰا وَءَالَ إِبۡرَ ٰهِیمَ وَءَالَ عِمۡرَ ٰنَ عَلَى ٱلۡعَـٰلَمِینَ

ذُرِّیَّةَۢ بَعۡضُهَا مِنۢ بَعۡضࣲۗ وَٱللَّهُ سَمِیعٌ عَلِیمٌ

Reference  : Quran: Ali 'Imran 3:33-34
 
Quran 6:83-87: Allah swt chose from the descendents of Ibrahim. Their offspring and brethren. They were favoured over all of mankind.
Quran: Al-An'am 6:83-87
Translation: Tafheem-ul-Quran - Abul Ala Maududi

83: That was Our argument which We gave to Abraham against his people. We raise in ranks whom We will. Truly your lord is All-Wise, All-Knowing.

 

84: And We bestowed upon Abraham (offspring) Ishaq (Isaac) and Ya'qub (Jacob) and each of them did We guide to the right way as We had earlier guided Noah to the right way; and (of his descendants We guided) Da'ud (David) and Sulayman (Solomon), Ayyub (Job), Yusuf (Joseph), Musa (Moses) and Harun (Aaron). Thus do We reward those who do good.

 

85: (And of his descendants We guided) Zakariya (Zachariah), Yahya (John), Isa (Jesus) and Ilyas (Elias): each one of them was of the righteous.

 

86: (And of his descendants We guided) Isma'il (Ishmael), al-Yasa' (Elisha), Yunus (Jonah), and Lut (Lot). And each one of them We favoured over all mankind.

 

87: And likewise We chose for Our cause and guided on to a straight way some of their forefathers and their offspring and their brethren.

وَتِلۡكَ حُجَّتُنَاۤ ءَاتَیۡنَـٰهَاۤ إِبۡرَ ٰهِیمَ عَلَىٰ قَوۡمِهِۦۚ نَرۡفَعُ دَرَجَـٰتࣲ مَّن نَّشَاۤءُۗ إِنَّ رَبَّكَ حَكِیمٌ عَلِیمࣱ

وَوَهَبۡنَا لَهُۥۤ إِسۡحَـٰقَ وَیَعۡقُوبَۚ كُلًّا هَدَیۡنَاۚ وَنُوحًا هَدَیۡنَا مِن قَبۡلُۖ وَمِن ذُرِّیَّتِهِۦ دَاوُۥدَ وَسُلَیۡمَـٰنَ وَأَیُّوبَ وَیُوسُفَ وَمُوسَىٰ وَهَـٰرُونَۚ وَكَذَ ٰلِكَ نَجۡزِی ٱلۡمُحۡسِنِینَ

وَزَكَرِیَّا وَیَحۡیَىٰ وَعِیسَىٰ وَإِلۡیَاسَۖ كُلࣱّ مِّنَ ٱلصَّـٰلِحِینَ

وَإِسۡمَـٰعِیلَ وَٱلۡیَسَعَ وَیُونُسَ وَلُوطࣰاۚ وَكُلࣰّا فَضَّلۡنَا عَلَى ٱلۡعَـٰلَمِینَ

وَمِنۡ ءَابَاۤىِٕهِمۡ وَذُرِّیَّـٰتِهِمۡ وَإِخۡوَ ٰنِهِمۡۖ وَٱجۡتَبَیۡنَـٰهُمۡ وَهَدَیۡنَـٰهُمۡ إِلَىٰ صِرَ ٰطࣲ مُّسۡتَقِیمࣲ

Reference  : Quran: Al-An'am 6:83-87
Ibrahim prays for a nation submissive to Allah swt from among his descendants.
Quran 2:127-129 Ibrahim prays for a nation from his descendants who are submissive to Allah swt.
Quran: Al-Baqara 2:127-129
Translation: Abridged Explanation of the Quran

127: And when Ibrahim was raising up the foundations of the House, along with Ismail: "Our Lord accept from us! Indeed, You - and You alone - are the All-Hearing, the All-Knowing!"

 

128: And, our Lord, make us both submissive to You, and of1 our progeny a nation2 submissive to You. And show us our ways of Pilgrimage and accept our repentance. Indeed, You - and You alone - are the Most-Relenting, the Very-Merciful."

 

129: And, our Lord, raise in their midst3 a Messenger from among them [the submissive nation], who should recite to them Your verses, and teach them the Book and the wisdom, and make them pure. Indeed You and You alone, are the All-Mighty, the All-Wise.

وَإِذۡ یَرۡفَعُ إِبۡرَ ٰهِـۧمُ ٱلۡقَوَاعِدَ مِنَ ٱلۡبَیۡتِ وَإِسۡمَـٰعِیلُ رَبَّنَا تَقَبَّلۡ مِنَّاۤۖ إِنَّكَ أَنتَ ٱلسَّمِیعُ ٱلۡعَلِیمُ

رَبَّنَا وَٱجۡعَلۡنَا مُسۡلِمَیۡنِ لَكَ وَمِن ذُرِّیَّتِنَاۤ أُمَّةࣰ مُّسۡلِمَةࣰ لَّكَ وَأَرِنَا مَنَاسِكَنَا وَتُبۡ عَلَیۡنَاۤۖ إِنَّكَ أَنتَ ٱلتَّوَّابُ ٱلرَّحِیمُ

رَبَّنَا وَٱبۡعَثۡ فِیهِمۡ رَسُولࣰا مِّنۡهُمۡ یَتۡلُوا۟ عَلَیۡهِمۡ ءَایَـٰتِكَ وَیُعَلِّمُهُمُ ٱلۡكِتَـٰبَ وَٱلۡحِكۡمَةَ وَیُزَكِّیهِمۡۖ إِنَّكَ أَنتَ ٱلۡعَزِیزُ ٱلۡحَكِیمُ

Note: 1. Clearly this verse cannot refer to all his children and descendents, as Abu Lahab too is a descendant of Ibrahim, as are the other children of Abd Manaf who died as kafirs. So, this can be interpreted as some of his descendants will become a nation submissive to Allah swt.

2. The word used here is Ummah, a nation. This submissive nation is exclusively from the children of Ibrahim, given the statement is prefaced by "and of/from our progeny." Hence, the verse is not talking about the Muslim Ummah at large, but a "nation," defined by those who are exclusively children of Ibrahim.

3. In the midst of the children of Ibrahim who were not submissive.

 
Quran 62:2: Allah swt answer's Ibrahim's dua, and states others will join the Prophet in the future.
Quran: Al-Jumu'ah 62:2
Translation: Maarif-ul-Quran

2: He is the One who raised amidst the unlettered people1 "a messenger from themselves [submissive nation] who recites to them His verses,2 and purifies them, and teaches them the Book and the wisdom," although they were3 in an open error before.

هُوَ ٱلَّذِی بَعَثَ فِی ٱلۡأُمِّیِّـۧنَ رَسُولࣰا مِّنۡهُمۡ یَتۡلُوا۟ عَلَیۡهِمۡ ءَایَـٰتِهِۦ وَیُزَكِّیهِمۡ وَیُعَلِّمُهُمُ ٱلۡكِتَـٰبَ وَٱلۡحِكۡمَةَ وَإِن كَانُوا۟ مِن قَبۡلُ لَفِی ضَلَـٰلࣲ مُّبِینࣲ

Reference  : Quran: Al-Jumu'ah 62:2

Note: 1. This first fragment is in the past tense. It indicates it is referring to one group of people - specifically the unlettered inhabitants of Mecca. Note they are "raised admist or among" the unlettered people, they're not from the unlettered people. Recall also from Quran 2:129 that Ibrahim says "raise in their midst" and hence this is directly related to the unlettered people.

2. Note the change in tense from past to present, indicating a different group of people. Note also that this fragment is an almost verbatum quote of Quran 2:129, and hence, we can conclude the people referred to in this fragment are indeed the Submissive Nation referred to in Quran 2:129.

3. Note again the change in tense, referring back to the first group of people, the unlettered people, not the submissive nation.

 
Bible: Genesis 17:20: The Bible states that Allah promises Ibrahim to make Ishmael a great nation

Reference: Bible: Genesis 17:20

Bible: Genesis 17:20
New International Version

And as for Ishmael, I have heard you: I will surely bless him; I will make him fruitful and will greatly increase his numbers. He will be the father of twelve rulers, and I will make him into a great nation.

New Living Translation

As for Ishmael, I will bless him also, just as you have asked. I will make him extremely fruitful and multiply his descendants. He will become the father of twelve princes, and I will make him a great nation.

Reference  : Bible: Genesis 17:20
 
Ibrahim was a nation, as is Muhammad. But Muhammad is the best nation ever brought forth from mankind.
Quran 16:120: Ibrahim was a nation by himself.

Reference: Quran: An-Nahl 16:120

Quran: An-Nahl 16:120
Translation: Mufti Taqi Usmani

Surely, Ibrāhīm was an Ummah (a whole nation in himself), devoted to Allah, a man of pure faith; and he was not among the Mushriks (i.e. those who associate partners with Allah)

إِنَّ إِبۡرَ ٰهِیمَ كَانَ أُمَّةࣰ قَانِتࣰا لِّلَّهِ حَنِیفࣰا وَلَمۡ یَكُ مِنَ ٱلۡمُشۡرِكِینَ

Reference  : Quran: An-Nahl 16:120
 
Quran 3:110: Allah swt tells the Prophet that he is the best nation brought forth from mankind.
Quran: Ali 'Imran 3:110
Translation: Saheeh International

108: These are the verses of Allāh. We recite them to you, [O Muḥammad], in truth; and Allāh wants no injustice to the worlds [i.e., His creatures].

 

109: To Allāh belongs whatever is in the heavens and whatever is on the earth. And to Allāh will [all] matters be returned.

 

110: You are the best nation produced [as an example] for mankind. You enjoin what is right and forbid what is wrong and believe in Allāh. If only the People of the Scripture3 had believed, it would have been better for them. Among them are believers, but most of them are defiantly disobedient.

تِلۡكَ ءَایَـٰتُ ٱللَّهِ نَتۡلُوهَا عَلَیۡكَ بِٱلۡحَقِّۗ وَمَا ٱللَّهُ یُرِیدُ ظُلۡمࣰا لِّلۡعَـٰلَمِینَ

وَلِلَّهِ مَا فِی ٱلسَّمَـٰوَ ٰتِ وَمَا فِی ٱلۡأَرۡضِۚ وَإِلَى ٱللَّهِ تُرۡجَعُ ٱلۡأُمُورُ

كُنتُمۡ خَیۡرَ أُمَّةٍ أُخۡرِجَتۡ لِلنَّاسِ تَأۡمُرُونَ بِٱلۡمَعۡرُوفِ وَتَنۡهَوۡنَ عَنِ ٱلۡمُنكَرِ وَتُؤۡمِنُونَ بِٱللَّهِۗ وَلَوۡ ءَامَنَ أَهۡلُ ٱلۡكِتَـٰبِ لَكَانَ خَیۡرࣰا لَّهُمۚ مِّنۡهُمُ ٱلۡمُؤۡمِنُونَ وَأَكۡثَرُهُمُ ٱلۡفَـٰسِقُونَ

Reference  : Quran: Ali 'Imran 3:110

Note: 1. From 3:108 it is the clear that the "You" in 3:110 is Muhammad himself, not the Muslim community in aggregate. Given that Ibrahim is promised a submissive nation from his descendents, and that the Prophet is the messenger from within this nation (Quran: 2:129), it necessitates that Muhammad's nation is from Quraysh, and specifically the descendants of Adb Manaf.

2. Note that 16:120 is past tense, whereas 3:110 is present tense, this best nation persists.

3. The Bible in Genesis 17-20 speaks of Allah swt granting Ibrahim's dua, wherein Allah swt will make Ishmael a great nation, and the father of twelve princes (Emirs).

 
Allah swt states that Muhammad's nation is a witness over mankind.
Quran 2:143: Allah swt has made this nation a witness over mankind, and he is a witness over them.
Quran: Al-Baqarah 2:143
Translation: Saheeh International

And thus We have made you a median [i.e., just] community [Ummah] that you will be witnesses over the people and the Messenger will be a witness over you. And We did not make the qiblah which you used to face except that We might make evident who would follow the Messenger from who would turn back on his heels.1 And indeed, it is difficult except for those whom Allāh has guided. And never would Allāh have caused you to lose your faith. Indeed Allāh is, to the people, Kind and Merciful.

وَكَذَ ٰلِكَ جَعَلۡنَـٰكُمۡ أُمَّةࣰ وَسَطࣰا لِّتَكُونُوا۟ شُهَدَاۤءَ عَلَى ٱلنَّاسِ وَیَكُونَ ٱلرَّسُولُ عَلَیۡكُمۡ شَهِیدࣰاۗ وَمَا جَعَلۡنَا ٱلۡقِبۡلَةَ ٱلَّتِی كُنتَ عَلَیۡهَاۤ إِلَّا لِنَعۡلَمَ مَن یَتَّبِعُ ٱلرَّسُولَ مِمَّن یَنقَلِبُ عَلَىٰ عَقِبَیۡهِۚ وَإِن كَانَتۡ لَكَبِیرَةً إِلَّا عَلَى ٱلَّذِینَ هَدَى ٱللَّهُۗ وَمَا كَانَ ٱللَّهُ لِیُضِیعَ إِیمَـٰنَكُمۡۚ إِنَّ ٱللَّهَ بِٱلنَّاسِ لَرَءُوفࣱ رَّحِیمࣱ

Reference  : Quran: Al-Baqarah 2:143
 
Quran 22:78: Ibrahim is the father of this nation that Allah swt has made witnesses over the people.

Reference: Quran: Al-Hajj 22:78

Quran: Al-Hajj 22:78
Translation: Dr. Mustafa Khattab

Strive for ˹the cause of˺ Allah in the way He deserves,1 for ˹it is˺ He ˹Who˺ has chosen you,2 and laid upon you no hardship in the religion — the way of your forefather Abraham.3 ˹It is Allah˺ Who named you ‘the ones who submit’ ˹in the˺ earlier ˹Scriptures˺4 and in this ˹Quran˺, so that the Messenger may be a witness over you, and that you may be witnesses over humanity. So establish prayer, pay alms-tax, and hold fast to Allah. He ˹alone˺ is your Guardian. What an excellent Guardian, and what an excellent Helper!

وَجَـٰهِدُوا۟ فِی ٱللَّهِ حَقَّ جِهَادِهِۦۚ هُوَ ٱجۡتَبَىٰكُمۡ وَمَا جَعَلَ عَلَیۡكُمۡ فِی ٱلدِّینِ مِنۡ حَرَجࣲۚ مِّلَّةَ أَبِیكُمۡ إِبۡرَ ٰهِیمَۚ هُوَ سَمَّىٰكُمُ ٱلۡمُسۡلِمِینَ مِن قَبۡلُ وَفِی هَـٰذَا لِیَكُونَ ٱلرَّسُولُ شَهِیدًا عَلَیۡكُمۡ وَتَكُونُوا۟ شُهَدَاۤءَ عَلَى ٱلنَّاسِۚ فَأَقِیمُوا۟ ٱلصَّلَوٰةَ وَءَاتُوا۟ ٱلزَّكَوٰةَ وَٱعۡتَصِمُوا۟ بِٱللَّهِ هُوَ مَوۡلَىٰكُمۡۖ فَنِعۡمَ ٱلۡمَوۡلَىٰ وَنِعۡمَ ٱلنَّصِیرُ

Reference  : Quran: Al-Hajj 22:78

Note: 1. The order is to strive in the way in which He deserves. While the general ummah may have strive, they're incapable of striving in the way Allah swt deserves.

2. That is why they are chosen by Allah swt

3. Ibrahim is father is this nation that will be witnesses over mankind. Ibrahim is not the father of all muslims, and therefore, the "ummahatan wasata" referred to in Quran 2:143 cannot be the general Ummah at large.

4. The descendants of Ibrahim and Allah's covenant with them are discussed in earlier scriptures, namely the Bible.

 
Who are this nation?
Quran 2:124: Allah appoints Ibrahim an Imam. While His covenant extends to Ibrahim's descendents, it does not extend to the wrong-doers.
Quran: Al-Baqarah 2:124
Translation: Tafheem-ul-Quran - Abul Ala Maududi

Recall when Abraham’s Lord tested him in certain matters and when he successfully stood the test, He said: “Indeed I am going to appoint you an Imam of all people.” When Abraham asked: “And is this covenant also for my descendants?” the Lord responded: “My covenant does not embrace the wrong-doers.”

وَإِذِ ٱبۡتَلَىٰۤ إِبۡرَ ٰهِـۧمَ رَبُّهُۥ بِكَلِمَـٰتࣲ فَأَتَمَّهُنَّۖ قَالَ إِنِّی جَاعِلُكَ لِلنَّاسِ إِمَامࣰاۖ قَالَ وَمِن ذُرِّیَّتِیۖ قَالَ لَا یَنَالُ عَهۡدِی ٱلظَّـٰلِمِینَ

Reference  : Quran: Al-Baqarah 2:124
 
The Prophet (ﷺ) said: There will be twelve Emir after me, all from Quraish.
Sahih al-Bukhari 3092
Simak bin Harb narrated from Jabir bin Samurah who said " The Messenger of Allah(s.a.w) said:

'There will be twelve Emir after me."' He said: "Then he said something that I did not understand. So I asked the one who was next to me, who said that he(s.a.w) had said: 'All of them are from Quraish."'

حَدَّثَنَا أَبُو كُرَيْبٍ، مُحَمَّدُ بْنُ الْعَلاَءِ حَدَّثَنَا عُمَرُ بْنُ عُبَيْدٍ الطَّنَافِسِيُّ، عَنْ سِمَاكِ بْنِ حَرْبٍ، عَنْ جَابِرِ بْنِ سَمُرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ يَكُونُ مِنْ بَعْدِي اثْنَا عَشَرَ أَمِيرًا ‏"‏ ‏.‏ قَالَ ثُمَّ تَكَلَّمَ بِشَيْءٍ لَمْ أَفْهَمْهُ فَسَأَلْتُ الَّذِي يَلِينِي فَقَالَ قَالَ ‏"‏ كُلُّهُمْ مِنْ قُرَيْشٍ ‏"‏ ‏.‏ قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ ‏.‏ حَدَّثَنَا أَبُو كُرَيْبٍ، حَدَّثَنَا عُمَرُ بْنُ عُبَيْدٍ، عَنْ أَبِيهِ، عَنْ أَبِي بَكْرِ بْنِ أَبِي مُوسَى، عَنْ جَابِرِ بْنِ سَمُرَةَ، عَنِ النَّبِيِّ صلى الله عليه وسلم مِثْلَ هَذَا الْحَدِيثِ وقَدْ رُوِيَ مِنْ غَيْرِ وَجْهٍ عَنْ جَابِرِ بْنِ سَمُرَةَ ‏.‏ قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ غَرِيبٌ يُسْتَغْرَبُ مِنْ حَدِيثِ أَبِي بَكْرِ بْنِ أَبِي مُوسَى عَنْ جَابِرِ بْنِ سَمُرَةَ ‏.‏ وَفِي الْبَابِ عَنِ ابْنِ مَسْعُودٍ وَعَبْدِ اللَّهِ بْنِ عَمْرٍو ‏.‏
Grade: Sahih (Darussalam)
Reference  : Jami' at-Tirmidhi 2223
In-book reference  : Book 33, Hadith 66

Note: The descendants of Ibrahim were the people of Quraish, specifically the descendents of Abd Manaf, the great great grandfather of the Prophet. The Ummayid's, while descendents of Abd Manaf and hence Ibrahim, are well documented wrong-doers, as were the Abbasids.

 
Bible Genesis 17:20: The Bible states that Allah promises Ibrahim Ishmael will be the father of 12 rulers or princes.

Reference: Bible: Genesis 17:20

Bible: Genesis 17:20
New International Version

And as for Ishmael, I have heard you: I will surely bless him; I will make him fruitful and will greatly increase his numbers. He will be the father of twelve rulers, and I will make him into a great nation.

New Living Translation

As for Ishmael, I will bless him also, just as you have asked. I will make him extremely fruitful and multiply his descendants. He will become the father of twelve princes, and I will make him a great nation.

Reference  : Bible: Genesis 17:20
 
Quran 33:33: Allah purifies the AhlulBayt from sin. Only they fulfill the requirements established by Allah swt for leadership.

Reference: Quran: Al-Ahzab 33:33

Quran: Al-Ahzab 33:33
Translation: Saheeh International

Allah intends only to remove from you the impurity [of sin], O people of the AhlulBayt (Prophet's household), and to purify you with [extensive] purification.

 
Translation: Dr. Mustafa Khattab, the Clear Quran

Allah only intends to keep ˹the causes of˺ evil away from you and purify you completely, O AhlulBayt (members of the ˹Prophet’s˺ family).

 
Translation: Pickthall

Allah's wish is but to remove uncleanness far from you, O AhlulBayt (Folk of the Household), and cleanse you with a thorough cleansing.

‏وَقَرْنَ فِى بُيُوتِكُنَّ وَلَا تَبَرَّجْنَ تَبَرُّجَ ٱلْجَهِلِيَّةِ ٱلْأُولَىٰۖ وَأَقِمْنَ ٱلصَّلَوٰةَ وَءَاتِينَ ٱلزَّكَوٰةَ وَأَطِعْنَ ٱللَّهَ وَرَسُولَهُۚۥٓ إِنَّمَا يُرِيدُ ٱللَّهُ لِيُذْهِبَ عَنكُمُ ٱلرِّجْسَ أَهْلَ ٱلْبَيْتِ وَيُطَهِّرَكُمْ تَطْهِيرًۭا
Reference  : Quran: Al-Ahzab 33:33

Note: No other descendents, except the AhlulBayt of Prophet Muhammad are purified from sin, and therefore, none other fulfill the requirements of Allah swt's covenant with Ibrahim to whom Imamah will be granted.

 
We are commanded to ask Allah swt to bless Muhammad's household the way he blessed Ibrahim's household.
Quran 33:56: O believers! Invoke Allah’s blessings upon him (Rasulullah), and salute him with worthy greetings of peace.

Reference: Quran: Al-Ahzab 33:56

Quran: Al-Ahzab (33:56)
Dr. Mustafa Khattab, the Clear Quran

Indeed, Allah showers His blessings upon the Prophet, and His angels pray for him. O believers! Invoke Allah’s blessings upon him, and salute him with worthy greetings of peace.

إِنَّ ٱللَّهَ وَمَلَٓئِكَتَهُۥ يُصَلُّونَ عَلَى ٱلنَّبِىِّۚ يَٓأَيُّهَا ٱلَّذِينَ ءَامَنُوا۟ صَلُّوا۟ عَلَيْهِ وَسَلِّمُوا۟ تَسْلِيمًا
Reference  : Quran: Al-Ahzab 33:56
 
Bashir b. S'ad said: Allah has commanded us to bless you. Messenger of Allah! But how should we bless you?

Reference: Sahih Muslim 405

Sahih Muslim 405
Abdullah b. Zaid-he who was shown the call (for prayer in a dream) narrated it on the authority of Abu Mas'ud al-Ansari who said:

We were sitting in the company of Sa'id b. 'Ubida when the Messenger of Allah (ﷺ) came to us. Bashir b. S'ad said: Allah has commanded us to bless you. Messenger of Allah! But how should we bless you? He (the narrator) said: The Messenger of Allah (ﷺ) kept quiet (and we were so much perturbed over his silence) that we wished we had not asked him. The Messenger of Allah (ﷺ) then said: (For blessing me) say: "O Allah, bless Muhammad and the members of his household as Thou didst bless the members of Ibrahim's household. Grant favours to Muhammad and the members of his household as Thou didst grant favours to the members of the household of Ibrahim in the world. Thou art indeed Praiseworthy and Glorious" ; and salutation as you know.

 

Transliteration: Alahumma salli 'ala Muhammad wa 'ala ali Muhammad, kama sallaita 'ala Ibrahima wa barik 'ala Muhammad wa 'ala ali Muhammad kama barakta 'ala ali Ibrahim fil-'alamin, innaka hamidun majid.

حَدَّثَنَا يَحْيَى بْنُ يَحْيَى التَّمِيمِيُّ، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ نُعَيْمِ بْنِ عَبْدِ اللَّهِ الْمُجْمِرِ، أَنَّ مُحَمَّدَ بْنَ عَبْدِ اللَّهِ بْنِ زَيْدٍ الأَنْصَارِيَّ، - وَعَبْدُ اللَّهِ بْنُ زَيْدٍ هُوَ الَّذِي كَانَ أُرِيَ النِّدَاءَ بِالصَّلاَةِ - أَخْبَرَهُ عَنْ أَبِي مَسْعُودٍ الأَنْصَارِيِّ قَالَ أَتَانَا رَسُولُ اللَّهِ صلى الله عليه وسلم وَنَحْنُ فِي مَجْلِسِ سَعْدِ بْنِ عُبَادَةَ فَقَالَ لَهُ بَشِيرُ بْنُ سَعْدٍ أَمَرَنَا اللَّهُ تَعَالَى أَنْ نُصَلِّيَ عَلَيْكَ يَا رَسُولَ اللَّهِ فَكَيْفَ نُصَلِّي عَلَيْكَ قَالَ فَسَكَتَ رَسُولُ اللَّهِ صلى الله عليه وسلم حَتَّى تَمَنَّيْنَا أَنَّهُ لَمْ يَسْأَلْهُ ثُمَّ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم قُولُوا ‏ "‏ اللَّهُمَّ صَلِّ عَلَى مُحَمَّدٍ وَعَلَى آلِ مُحَمَّدٍ كَمَا صَلَّيْتَ عَلَى آلِ إِبْرَاهِيمَ وَبَارِكْ عَلَى مُحَمَّدٍ وَعَلَى آلِ مُحَمَّدٍ كَمَا بَارَكْتَ عَلَى آلِ إِبْرَاهِيمَ فِي الْعَالَمِينَ إِنَّكَ حَمِيدٌ مَجِيدٌ ‏.‏ وَالسَّلاَمُ كَمَا قَدْ عَلِمْتُمْ ‏"‏ ‏.‏
Reference  : Sahih Muslim 405
In-book reference  : Book 4, Hadith 69

Note: The fact that we have been commanded by Allah swt to ask Him to bless the Prophet's household the way he has blessed Ibrahim's household makes clear that Muhammad's Ummah can only consist of members from his household, his Ahlulbayt, and not from any of the other members of Quraysh.

 
What are the consequences of differing with or rejecting this nation?
Quran 3:103-106: Hold firm to the rope of Allah, and do not become divided.
Quran: Ali 'Imran 3:103-106
Translation: Saheeh International

103: And hold firmly to the rope of Allāh all together and do not become divided1. And remember the favor of Allāh upon you - when you were enemies and He brought your hearts together and you became, by His favor, brothers. And you were on the edge of a pit of the Fire, and He saved you from it. Thus does Allāh make clear to you His verses that you may be guided.

 

104: And let there be [arising] from you a nation2 inviting to [all that is] good, enjoining what is right and forbidding what is wrong,1 and those will be the successful.

 

105: And do not be like the ones who became divided and differed after the clear proofs had come to them.3 And those will have a great punishment.

 

106: On the Day [some] faces will turn white and [some] faces will turn black. As for those whose faces turn black, [to them it will be said], "Did you disbelieve [i.e., reject faith] after your belief?4 Then taste the punishment for what you used to reject."

وَٱعۡتَصِمُوا۟ بِحَبۡلِ ٱللَّهِ جَمِیعࣰا وَلَا تَفَرَّقُوا۟ۚ وَٱذۡكُرُوا۟ نِعۡمَتَ ٱللَّهِ عَلَیۡكُمۡ إِذۡ كُنتُمۡ أَعۡدَاۤءࣰ فَأَلَّفَ بَیۡنَ قُلُوبِكُمۡ فَأَصۡبَحۡتُم بِنِعۡمَتِهِۦۤ إِخۡوَ ٰنࣰا وَكُنتُمۡ عَلَىٰ شَفَا حُفۡرَةࣲ مِّنَ ٱلنَّارِ فَأَنقَذَكُم مِّنۡهَاۗ كَذَ ٰلِكَ یُبَیِّنُ ٱللَّهُ لَكُمۡ ءَایَـٰتِهِۦ لَعَلَّكُمۡ تَهۡتَدُونَ

وَلۡتَكُن مِّنكُمۡ أُمَّةࣱ یَدۡعُونَ إِلَى ٱلۡخَیۡرِ وَیَأۡمُرُونَ بِٱلۡمَعۡرُوفِ وَیَنۡهَوۡنَ عَنِ ٱلۡمُنكَرِۚ وَأُو۟لَـٰۤىِٕكَ هُمُ ٱلۡمُفۡلِحُونَ

وَلَا تَكُونُوا۟ كَٱلَّذِینَ تَفَرَّقُوا۟ وَٱخۡتَلَفُوا۟ مِنۢ بَعۡدِ مَا جَاۤءَهُمُ ٱلۡبَیِّنَـٰتُۚ وَأُو۟لَـٰۤىِٕكَ لَهُمۡ عَذَابٌ عَظِیمࣱ

یَوۡمَ تَبۡیَضُّ وُجُوهࣱ وَتَسۡوَدُّ وُجُوهࣱۚ فَأَمَّا ٱلَّذِینَ ٱسۡوَدَّتۡ وُجُوهُهُمۡ أَكَفَرۡتُم بَعۡدَ إِیمَـٰنِكُمۡ فَذُوقُوا۟ ٱلۡعَذَابَ بِمَا كُنتُمۡ تَكۡفُرُونَ

Note: 1. The instruction to not be divided makes clear that the Muslims at large are being addressed.

2. Let a nation emerge from within the larger Muslim ummah, do not divide from them. This make it clear that this is referring again to the submissive nation from the descendents of Ibrahim.

3. Allah swt warns again not to become divided from this nation. Here the rejecting Muslims are being compared to the People of the Book.

4. Rejection of this nation is tantamount to disbelief.

 
Who are the members of the Ahlulbayt?
A'isha identifies the members of the AhlulBayt, and who, specifically, was purified in Quran 33:33

Reference: Sahih Muslim 2424

Sahih Muslim 2424
`A'isha reported:

that Allah's Apostle (ﷺ) went out one norning wearing a striped cloak of the black camel's hair that there came Hasan b. 'Ali. He wrapped hitn under it, then came Husain and he wrapped him under it along with the other one (Hasan). Then came Fatima and he took her under it, then came 'Ali and he also took him under it and then said:

Allah only desires to take away any uncleanliness from you, O people of the household (AhlulBayt), and purify you (thorough purifying) - (Quran 33:33)

حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، وَمُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ نُمَيْرٍ، - وَاللَّفْظُ لأَبِي بَكْرٍ - قَالاَ حَدَّثَنَا مُحَمَّدُ بْنُ بِشْرٍ، عَنْ زَكَرِيَّاءَ، عَنْ مُصْعَبِ بْنِ شَيْبَةَ، عَنْ صَفِيَّةَ بِنْتِ شَيْبَةَ، قَالَتْ قَالَتْ عَائِشَةُ خَرَجَ النَّبِيُّ صلى الله عليه وسلم غَدَاةً وَعَلَيْهِ مِرْطٌ مُرَحَّلٌ مِنْ شَعْرٍ أَسْوَدَ فَجَاءَ الْحَسَنُ بْنُ عَلِيٍّ فَأَدْخَلَهُ ثُمَّ جَاءَ الْحُسَيْنُ فَدَخَلَ مَعَهُ ثُمَّ جَاءَتْ فَاطِمَةُ فَأَدْخَلَهَا ثُمَّ جَاءَ عَلِيٌّ فَأَدْخَلَهُ ثُمَّ قَالَ ‏{‏ إِنَّمَا يُرِيدُ اللَّهُ لِيُذْهِبَ عَنْكُمُ الرِّجْسَ أَهْلَ الْبَيْتِ وَيُطَهِّرَكُمْ تَطْهِيرًا‏}‏‏
Reference  : Sahih Muslim 2424
In-book reference  : Book 44, Hadith 91
 
Corroborating Reference from the step-son of Rasulullah(ﷺ):
Jami` at-Tirmidhi 3205
Narrated 'Umar bin Abi Salamah - the step-son of the Prophet (ﷺ):

"When these Ayat were revealed to the Prophet (ﷺ): 'Allah only wishes to remove the Rijs from you, O members of the family, and to purify you with a thorough purification (33:33)' in the home of Umm Salamah, he called for Fatimah, Hasan, Husain, and wrapped him in the cloak, and 'Ali was behind him, so he wrapped him in the cloak, then he said: 'O Allah! These are the people of my house, so remove the Rijs from them, and purify them with a thorough purification.' So Umm Salamah said: 'And I, Prophet of Allah?' He said: 'You are in your place and you are goodness.'"

حَدَّثَنَا قُتَيْبَةُ، حَدَّثَنَا مُحَمَّدُ بْنُ سُلَيْمَانَ بْنِ الأَصْبَهَانِيِّ، عَنْ يَحْيَى بْنِ عُبَيْدٍ، عَنْ عَطَاءِ بْنِ أَبِي رَبَاحٍ، عَنْ عُمَرَ بْنِ أَبِي سَلَمَةَ، رَبِيبِ النَّبِيِّ صلى الله عليه وسلم قَالَ لَمَّا نَزَلَتْ هَذِهِ الآيَةُ عَلَى النَّبِيِّ صلى الله عليه وسلمَّ ‏:‏ ‏(‏ إنمَا يُرِيدُ اللَّهُ لِيُذْهِبَ عَنْكُمُ الرِّجْسَ أَهْلَ الْبَيْتِ وَيُطَهِّرَكُمْ تَطْهِيرًا ‏)‏ فِي بَيْتِ أُمِّ سَلَمَةَ فَدَعَا فَاطِمَةَ وَحَسَنًا وَحُسَيْنًا فَجَلَّلَهُمْ بِكِسَاءٍ وَعَلِيٌّ خَلْفَ ظَهْرِهِ فَجَلَّلَهُمْ بِكِسَاءٍ ثُمَّ قَالَ ‏"‏ اللَّهُمَّ هَؤُلاَءِ أَهْلُ بَيْتِي فَأَذْهِبْ عَنْهُمُ الرِّجْسَ وَطَهِّرْهُمْ تَطْهِيرًا ‏"‏ ‏.‏ قَالَتْ أُمُّ سَلَمَةَ وَأَنَا مَعَهُمْ يَا نَبِيَّ اللَّهِ قَالَ ‏"‏ أَنْتِ عَلَى مَكَانِكِ وَأَنْتِ عَلَى خَيْرٍ ‏"‏ ‏.‏ قَالَ هَذَا حَدِيثٌ غَرِيبٌ مِنْ هَذَا الْوَجْهِ مِنْ حَدِيثِ عَطَاءٍ عَنْ عُمَرَ بْنِ أَبِي سَلَمَةَ ‏.‏
Grade: Sahih (Darussalam)
Reference  : Jami` at-Tirmidhi 3205
In-book reference  : Book 47, Hadith 257
 
Are the wives of the Prophet included in the Ahlulbayt?
The Wives are not included in the Ahlulbayt.

Reference: Sahih Muslim 2408d

Sahih Muslim 2408d
Yazid b. Hayyan reported:

We went to him (Zaid b. Arqam) and said to him. You have found goodness (for you had the honour) to live in the company of Allah's Messenger (ﷺ) and offered prayer behind him, and the rest of the hadith is the same but with this variation of wording that said: Behold, for I am leaving amongst you two weighty things, one of which is the Book of Allah, the Exalted and Glorious, and that is the rope of Allah. He who holds it fast would be on right guidance and he who abandons it would be in error, and in this (hadith) these words are also found: We said: Who are amongst the members of the household? Aren't the wives (of the Holy Prophet) included amongst the members of his house hold? Thereupon he said: No, by Allah, a woman lives with a man (as his wife) for a certain period; he then divorces her and she goes back to her parents and to her people; the members of his household include his ownself and his kith and kin (who are related to him by blood) and for him the acceptance of Zakat is prohibited.

حَدَّثَنَا مُحَمَّدُ بْنُ بَكَّارِ بْنِ الرَّيَّانِ، حَدَّثَنَا حَسَّانُ، - يَعْنِي ابْنَ إِبْرَاهِيمَ - عَنْ سَعِيدٍ، - وَهُوَ ابْنُ مَسْرُوقٍ - عَنْ يَزِيدَ بْنِ حَيَّانَ، عَنْ زَيْدِ بْنِ أَرْقَمَ، قَالَ دَخَلْنَا عَلَيْهِ فَقُلْنَا لَهُ لَقَدْ رَأَيْتَ خَيْرًا ‏.‏ لَقَدْ صَاحَبْتَ رَسُولَ اللَّهِ صلى الله عليه وسلم وَصَلَّيْتَ خَلْفَهُ ‏.‏ وَسَاقَ الْحَدِيثَ بِنَحْوِ حَدِيثِ أَبِي حَيَّانَ غَيْرَ أَنَّهُ قَالَ ‏ "‏ أَلاَ وَإِنِّي تَارِكٌ فِيكُمْ ثَقَلَيْنِ أَحَدُهُمَا كِتَابُ اللَّهِ عَزَّ وَجَلَّ هُوَ حَبْلُ اللَّهِ مَنِ اتَّبَعَهُ كَانَ عَلَى الْهُدَى وَمَنْ تَرَكَهُ كَانَ عَلَى ضَلاَلَةٍ ‏"‏ ‏.‏ وَفِيهِ فَقُلْنَا مَنْ أَهْلُ بَيْتِهِ نِسَاؤُهُ قَالَ لاَ وَايْمُ اللَّهِ إِنَّ الْمَرْأَةَ تَكُونُ مَعَ الرَّجُلِ الْعَصْرَ مِنَ الدَّهْرِ ثُمَّ يُطَلِّقُهَا فَتَرْجِعُ إِلَى أَبِيهَا وَقَوْمِهَا أَهْلُ بَيْتِهِ أَصْلُهُ وَعَصَبَتُهُ الَّذِينَ حُرِمُوا الصَّدَقَةَ بَعْدَهُ ‏.
Reference  : Sahih Muslim 2408d
In-book reference  : Book 44, Hadith 58

Note: We now understand that the wives of the Prophet cannot be included in the Ahlulbayt, as they were not descendants of Ibrahim, a necessary criteria, as established above.