It is narrated from Sayyiduna Anas bin Malik (may Allah be pleased with him) that when the Messenger of Allah (peace and blessings be upon him) went out for the Fajr prayer, he would pass by the house of Sayyidah Fatimah (may Allah be pleased with her) for six months and say: "It is time for prayer," and he would recite this verse: "Allah only intends to remove impurity from you, O People of the House, and to purify you thoroughly" [Surah al-Ahzab: 33].
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 19205