Musannaf Ibn Abi Shayba 27:464

Muhammad ibn Bishr narrated to us, from Zakariya, from Mus'ab ibn Shaybah, from Safiyyah bint Shaybah, who said: Aishah said: The Prophet, may Allah bless him and grant him peace, went out one morning wearing a striped cloak made of black hair. Then al-Hasan came, and he brought him in with him. Then al-Husayn came, and he brought him in with him. Then Fatimah came, and he brought her in. Then Ali came, and he brought him in. Then he said: "Allah only wishes to remove from you [all] impurity, O people of the [Prophet's] household, and to purify you with [extensive] purification."