رَوَى الثَّعْلَبِيُّ فِي تَفْسِيرِ هَذِهِ الْآيَةِ تَعْيِينَ آلِ مُحَمَّدٍ ﷺ مِنْ طُرُقٍ فَمِنْهَا عَنْ اُمِّ سَلَمَةَ عَنْ رَسُولِ اللّهِ ﷺ اَنَّهُ قَالَ لِفَاطِمَةَ ايتِنِي [ايتِينِي] بِزَوْجِكِ وَ ابْنَيْكِ فَاَتَتْ بِهِمْ فَاَلْقَى عَلَيْهِمْ كِسَاءً ثُمَّ رَفَعَ يَدَهُ عَلَيْهِمْ فَقَالَ اللَّهُمَّ هَؤُلَاءِ آلُ مُحَمَّدٍ فَاجْعَلْ صَلَوَاتِكَ وَ بَرَكَاتِكَ عَلٰى آلِ مُحَمَّدٍ فَاِنَّكَ حَمِيدٌ مَجِيدٌ قَالَتْ فَرَفَعْتُ الْكِسَاءَ لِاَدْخُلَ مَعَهُمْ فَاجْتَذَبَهُ وَ قَالَ اِنَّكِ لَعَلَى خَيْرٍ
Al-Tha’labi – the famous commentator of Ahl Tasannun– in his exegesis under the verse of purification reports on the authority of Umm Salmah – one of the best wives of the Holy Prophet (peace be upon him and his holy progeny) after Hazrat Khadijah (peace be upon her) – from the Messenger of Allah (peace be upon him and his holy progeny) who said to Fatima (peace be upon her), “Bring to me your husband and your two sons.” She brought them. He (peace be upon him and his holy progeny) put a cloak on them. Thereafter, he (peace be upon him and his holy progeny) put his hand above them and invoked, “O Allah! These are the progeny of Muhammad. So put Your salutations and blessings upon the progeny of Muhammad. Surely, You are the Praiseworthy, the Majestic.” She (Umm Salmah) says, “I raised the cloak so that I could be with them.” He (peace be upon him and his holy progeny) put me away saying, ‘Surely, you are on goodness (but not deserving to be in this cloak’.”
This narration is called as the Hadis al-Kisaa. The reason for putting the cloak was to bring in exclusivity, so that none else in the house could claim being one of them. Remember, Umm Salmah (r.a.) was greater in position than an ordinary just and righteous person.
But in its exclusive meaning it implies the fourteen infallible guides (peace be upon him) including the Messenger of Allah (peace be upon him and his holy progeny).
Another point is that the Holy Prophet (peace be upon him and his holy progeny) said, “…upon Aale Muhammad” when he (peace be upon him and his holy progeny) could have said “…upon them’. The answer is that if he would have used the pronoun it would be restricted to the people under the cloak. But his repeating the progeny of Muhammad implied that it was for all the infallible ones from their progeny who are having all the perfections which the other four in the cloak had like wilayat takveeni, wilayat tashreei, tayyul arz, ilm ghaib, etc. i.e. those Imams (peace be upon them) who were not yet born.
1. Behaar al-Anwaar, vol. 23, p. 250, H. 24 narrating from sources of Ahl Tasannun.