The verse "Verily Allah intends to ... (33:33)" was revealed to the Prophet (PBUH&HF) in the house of Umm Salama. Upon that, the Prophet gathered Fatimah, al-Hasan, and al-Husain, and covered them with a cloak, and he also covered Ali who was behind him. Then the Prophet said: "O' Allah! These are the Members of my House (Ahlul-Bayt). Keep them away from every impurity and purify them with a perfect purification." Umm Salama (the wife of Prophet) asked: "Am I also included among them O Apostle of Allah?" the Prophet replied: "You remain in your position and you are toward a good ending."
Sunni reference: Sahih al-Tirmidhi, v5, pp 351,663
Ja'far Ibn Abi Talib narrated: When the Messenger of Allah noticed that a blessing from Allah was to descent, he told Safiyya (one of his wives): "Call for me! Call for me!" Safiyya said: "Call who, O the Messenger of Allah?" He said: "Call for me my Ahlul-Bayt who are Ali, Fatimah, al-Hasan, and al-Husain." Thus we sent for them and they came to him. Then the Prophet (PBUH&HF) spread his cloak over them, and raised his hand (toward sky) saying: "O Allah! These are my family (Aalee), so bless Muhammad and the family (Aal) of Muhammad." And Allah, to whom belong Might and Majesty, revealed: "Verily Allah intends to keep off from you every kind of uncleanness O' People of the House (Ahlul-Bayt), and purify you a thorough purification (Quran, the last sentence of Verse 33:33)".
Sunni references:al-Mustadrak by al-Hakim, Chapter of "Understanding (the virtues) of Companions, v3, p148. The author then wrote: "This tradition is authentic (Sahih) based on the criteria of the two Shaikhs (al-Bukhari and Muslim)."Talkhis of al-Mustadrak, by al-Dhahabi, v3, p148 Usdul Ghabah, by Ibn al-Athir, v3, p33
Umm Salama said: "O Prophet of Allah! Am I not one of the members of your family?" The Holy Prophet replied: "You have a good future but only these are the members of my family. O Lord! The members of my family are more deserving."
Sunni reference: al-Mustadrak, by al-Hakim, v2, p416
Umm Salama said to the Holy Prophet: "Am I also one of them?" He replied: "No. You have your own special position and your future is good."
Sunni references: Usdul Ghabah, by Ibn al-Athir, v2, p289; Tafsir al-Durr al-Manthoor, by al-Suyuti, v5, p198
al-Tabari quotes Umm Salama saying: I said, "O Prophet of Allah! Am I not also one of your Ahlul-Bayt?" I swear by the Almighty that the Holy Prophet did NOT grant me any distinction and said: "You have a good future."
Sunni references:Tafsir al-Tabari, v22, p7 under the commentary of verse 33:33
Narrated Yazid Ibn Hayyan: We went to Zaid Ibn Arqam and said to him: You have found goodness (for you had the honor) to live in the company of the Prophet (PBUH&HF) and offered prayer behind him, and the rest of the Hadith is the same (as 3 traditions before) but the Prophet said: "Behold, for I am leaving amongst you two weighty things, one of them is the Book of Allah...", and in this (Hadith) these words are also found: We said: "Who are his Ahlul-Bayt (that the Prophet was referring to)? Are they his wives?" Thereupon Zaid said: "No, by Allah! A woman lives with a man (as his wife) for a while; he then divorces her and she goes back to her parents and her people. The Ahlul-Bayt of the Prophet are his lineage and his descendants (those who come from his blood) for whom the acceptance of charity (Sadaqah) is prohibited."
Sunni reference: Sahih Muslim, Chapter of virtues of companions, section of the virtues of Ali, 1980 Edition Pub. in Saudi Arabia, Arabic version, v4, p1874, Tradition #37