Here I would like to bring another evidence from Sahih Muslim and Sahih al-Tirmidhi that why the wives of the Prophet are not included in Ahlul-Bayt, which is also, by the way, another reason for the superiority of Ali (AS) for the position of leadership after the Prophet (PBUH&HF).
The following incident is related to the event of "Mubahala" (which means imprecation, or invoking the curse of Allah upon the liar), which took place in the 9th-10th year of Hijrah. In that year a delegation consisting of 14 Christian priests came from Najran to meet the Prophet (PBUH&HF). When they met the Prophet they asked him what is his opinion about Jesus (AS). The Messenger of Allah (PBUH&HF) said: "You may take rest today and you will receive the reply afterwards." The next day, 3 verses of Quran (3:59-61) about Jesus were revealed. When Christians did not accept the words of Allah, The Prophet recited the last revealed verse:
But whoever disputes with you in this matter after what has come to you of knowledge, then say: Come let us call our sons and your sons, and our women and your women, and our selves and your selves; then let us be earnest in prayer and invoke the curse of Allah upon the liars. (Quran 3:61).
In this way, the Prophet (PBUH&HF) challenged the Christians. The next day the Christian priests came out on one side of the field. Also on the other side, the Prophet came out of his house carrying al-Husain in his arm with al-Hasan walking along with him while he was holding his hand. Behind him was Fatimah al-Zahra, and behind her was Ali, peace be upon them all. When the Christians saw the five pure souls, and how determined the Prophet is in his idea that he put the closest people to him at risk, the Christians were terrified and abstained from the proposed malediction (Mubahala) and submitted to a treaty with the Prophet (PBUH&HF).
al-Suyuti who was a great Sunni scholar, wrote:
In the above verse (3:61), according to what Jabir Ibn Abdillah al-Ansari (the great companion of the Prophet) said, the word "sons" refers to al-Hasan and al-Husain, the word "women" refers to Fatimah, and the word "our selves" refer to the Prophet and Ali. Thus Ali is referred as "the self" of the Prophet (Nafs of the Prophet).
Reference: al-Durr al-Manthoor by al-Hafidh Jalaluddin al-Suyuti, v2, p38
It follows that just as it is unlawful to seek to be superior to the Prophet, similarly it is unlawful to supersede Ali (who is the "self" of the Prophet according to the words of Allah). Any one who presumed to supersede Ali, was, in essence, presumed to supersede the Prophet! This is another Quranic proof for the right of Imam Ali as the immediate successor of the Prophet (PBUH&HF).
Muslim and al-Tirmidhi both confirm the above incident, and recorded the following tradition in their authentic collections of traditions:
Narrated Sa'd Ibn Abi Waqqas:
...And when the verse 3:61 was revealed, the Prophet called Ali, Fatimah, al-Hasan, and al-Husain. Then the Prophet said: "O Lord! These are my family members (Ahli)."
Sunni references:
Sahih Muslim, Chapter of virtues of companions, section of virtues of Ali, 1980 Edition Pub. in Saudi Arabia, Arabic version, v4, p1871, the end of tradition #32.
Sahih al-Tirmidhi, v5, p654
al-Mustadrak, by al-Hakim, v3, p150, who said this tradition is authentic based on the criteria set by two Shaikhs, al-Bukhari and Muslim.
Dhakha'ir al-Uqba, by Muhibbuddin al-Tabari, p25
Here is the Arabic text of the above tradition given by both
Sahih Muslim and Sahih al-Tirmidhi:
The point, here, is that the Messenger of Allah (PBUH&HF) did not bring any of his wives to the field of "Mubahala", and according to above tradition, he used the word "Ahl" (family) ONLY for the above-mentioned individuals (i.e., Imam Ali, Fatimah, al-Hasan, and al-Husain).
Note that in the verse 3:61 of Quran Allah uses plural form "women" by saying "Let us bring our women", but the Prophet only brought his daughter Fatimah (AS). If there were more than one woman in Ahlul-Bayt, the Prophet was required by this verse to bring them, but since there was not any other woman among his Ahlul-Bayt, he brought Fatimah (AS) only. Again, in that incident, the Prophet explicitly mentioned who Ahlul-Bayt are, and named them one by one, and Muslim, al-Tirmidhi, al-Hakim, and many other Sunni scholars recorded that and all confirmed its authenticity. There was no mention of his wives in any of these reports.
Some Sunni scholars have narrated that on the day of consultation for appointing the ruler after the death of Umar, Imam Ali (AS) argued with the members of Shura reminding them his rights to the Caliphate, and one of his reasons was the incident of Mubahala:
On the day of consultation, Ali argued with the committee members saying: "I adjure you in the name of Allah, is there anyone amongst you closer in relationship to the Messenger of Allah than me? Is there any other man whom the Prophet made him 'his (own) soul' (Nafs), and that he made his children 'his (own) children', and his women 'his (own) women'?" They replied: "No, by God!"
Sunni reference:
al-Darqunti, as per:
al-Sawa'iq al-Muhriqah, by Ibn Hajar al-Haythami, Ch. 11, section 1, p239
It is also narrated that:
The Prophet (PBUH&HF) said: "Verily, Allah, to whom belong Might and Majesty, has placed the progeny of each prophet into his backbone (Sulb), and He, Exalted, has placed my progeny into the backbone of Ali Ibn Abi Talib."
Sunni references:
al-Tabarani
Abul-Khair al-Haakimi, on the authority of al-Abbas
al-Sawa'iq al-Muhriqah, by Ibn Hajar al-Haythami, Ch. 11, section 1, p239
al-Kunooz al-Mataalib
It is also narrated that:
The Messenger of Allah (PBUH&HF) said: "Me and Ali are from one tree, and the rest of people are from different trees."
Sunni references:
al-Sawa'iq al-Muhriqah, by Ibn Hajar al-Haythami, Ch. 9, section 2, p190
Tarikh al-Khulafaa, by Jalaluddin al-Suyuti, p171
al-Awsat, by al-Tabarani, from Jabir Ibn Abdillah al-Ansari
In another Sunni commentary of Quran, it is narrated on the authority of Abdullah Ibn Umar that:
The Messenger of Allah (PBUH&HF) said: "Had there been any soul on the whole earth better than Ali, Fatimah, al-Hasan and al-Husain, Allah would have commanded me to take them along with me to Mubahala. But as they were superior in dignity and respect to all human be beings, Allah confined His choice on them only for participation in Mubahala."
Sunni reference: Tafsir al-Baidhawi, under the commentary of Verse 3:61
Concluding, the event of Mubahala between the Prophet (PBUH&HF) the Christians was significant in many aspects, among them are:
1.
It proved to be a lesson for all the Christians of Arabia who no longer dared any confrontation with the Holy Prophet (PBUH&HF).
2.
The invitation of "Mubahala" (literally meaning cursing each other) was directed by Allah and it was in compliance with His Command that the Holy Prophet and his Ahlul-Bayt along with him to the field of Mubahala. This serves to show how affairs pertaining to prophethood and Islam are determined by the Will of Allah; allowing no margin of interference from the common people (Ummah). (The matter of Imam Ali's (AS) succession after the Prophet should be viewed similarly)
3.
The indispensability of Imam Ali, Lady Fatimah, Imam al-Hasan and Imam al-Husain in the following of the precepts of the Holy Prophet could no longer be disputed.
4.
Notwithstanding their childhood, al-Hasan and al-Husain did nevertheless serve as two active partners of the Holy Prophet on the field of Mubahala. This yields the conclusion that age is no criteria for the greatness of those infallible souls.
5.
That the Holy Prophet's act of having preferred a few obviously elevates their status above all others.
6.
Traditions from the Prophet with regards to this event clearly indicates who the Ahlul-Bayt are.
7.
Imam Ali (AS) has been mentioned as the 'Self' of the Prophet (PBUH&HF) according to the revelation of Allah, and is, in fact, superior to all others with regard to the matter of succession.
Is It Just Blood Relationship?
It is narrated that:
The Messenger of Allah said: "Any relation will end on the day of Judgment except my relation. And the root (identification) of every one is his father, except the progeny of Fatimah, since I am their father and their root (identification)."
Sunni references:
Ibn al-Jawzi, al-Bayhaqi, and al-Darqunti, al-Dhahabi on the authorities of Umar Ibn al-Khattab, Ibn Abbas, Ibn Zubair, and Ibn Umar.
al-Sawa'iq al-Muhriqah, by Ibn Hajar al-Haythami, Ch. 11, section 1, p239
Similar tradition has been narrated by Abu Ya'la, al-Tabarani on the authority of Fatimah (AS) and Ibn Umar
The above precious tradition proves that, blood relationship is of little value in Islam and it will soon melt away when the day of Judgment appears. But what makes the relationship of the Prophet and his Ahlul-Bayt different than others is the qualifications and spiritual purity that they have besides their pure gene (which is also necessary).
It is worth mentioning that Lady Fatimah (AS) is the only surviving child of the Messenger of Allah (PBUH&HF) who left progeny for him. All other children of the Prophet died in their early ages, without being able to leave an issue behind themselves. The infidels of Hijaz (Arabia) used to dishonor the Prophet by saying that he does not have a son to preserve his generation. For that reason, Allah revealed the Chapter of "al-Kawthar":
"Lo! We have given you Abundance (i.e., a long-standing pure progeny). So pray unto your Lord, and sacrifice. Lo! It is your insulter (and not you) who is without progeny." (Quran, Chapter 108).
In the above Chapter, Allah refers to Fatimah al-Zahra as Abundance who brings for the Prophet a sanctified progeny. Again, by progeny we do not mean all those whose ancestor are the Prophet (PBUH&HF). We rather mean those among his descendants who have been thoroughly purified by Allah, and the history and the Hadith can not count more that 14 of them (including the Prophet). Here is the commentary of the above Chapter by Yusuf Ali (the translator of Quran):
Abu Jahl and his Pagan confederates vented their personal spite and venom against the holy Prophet by taunting him with the loss of his two infant sons by Khadija, but where were these venomous detractors a few years afterwards, when the divine Light shone more brilliantly than ever?
Fatimah received severe injuries and was martyred at the age of eighteen, just six months after the demise of the Prophet, leaving two sons: al-Hasan, and al-Husain. After martyrdom of Imam Ali (AS), Imam al-Hasan came to power. But Muawiyah, the disloyal governor of Syria, continued his aggression by preparing another attack (after the war of Siffin), and meanwhile he bought the key elements of the army of Imam al-Hasan by money and bribe, and by corrupting his army, was finally able to complete a peaceful military coup, and to take over the power. Imam al-Hasan was poisoned to death shortly after.
The second (and the last) grandson of the Prophet was Imam al-Husain (AS), who was slaughtered along with his family (except one of his sons), relatives, and companions, in the desert of Karbala, by the army of Yazid, the corrupt and drunk son of Muawiyah. That catastrophe took place only 50 years after the demise of the Prophet!!!
The above was a very short horrible story of what happened to Ahlul-Bayt, whom Quran and the Prophet (PBUH&HF) ordered us to love them and obey them beside the book of Allah.
source : http://www.al-islam.org