It is narrated from Sayyidah Umm Salamah (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) gathered Sayyidah Fatimah, Sayyiduna Hasan and Sayyiduna Husayn (may Allah be pleased with them), then brought them under his cloak, then said: "O Allah, these are my household (Ahl al-Bayt)." Sayyidah Umm Salamah (may Allah be pleased with her) said: I said: O Messenger of Allah, include me with them. He (peace and blessings be upon him) said: "You too are of my family."
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 2650