Musannaf Ibn Abi Shayba 27:465

Muhammad ibn Mus’ab narrated to us, from al-Awza’i, from Shaddad Abu ‘Ammar, who said: I entered upon Wathila while there were people with him, and they mentioned Ali and insulted him, so I insulted him with them. He said: "Shall I not inform you of what I heard from the Messenger of Allah, may Allah bless him and grant him peace?" I said: "Yes." He said: "I came to Fatima to ask her about Ali, and she said: 'He has gone to the Messenger of Allah, may Allah bless him and grant him peace.' So I sat down. Then the Messenger of Allah, may Allah bless him and grant him peace, came, and with him were Ali, Hasan, and Husayn, each of them holding his hand. He brought Ali and Fatima close and seated them in front of him, and he seated Hasan and Husayn, each of them on one of his thighs. Then he wrapped his garment—or he said his cloak—over them. Then he recited this verse: 'Allah only intends to remove from you the impurity, O people of the household.' Then he said: 'O Allah, these are the people of my household, and the people of my household are more deserving.'"