Sahih Muslim 1636

Yahya ibn Yahya and Abu Bakr ibn Abi Shaybah narrated to us—this is Yahya's wording. He said: Ismail ibn Ulayyah informed us from Ibn Awn, from Ibrahim, from al-Aswad ibn Yazid, who said: 'They mentioned in Aisha's presence that Ali had been appointed as the Prophet's trustee. She said, When did he appoint him? I was supporting him against my chest—or she said, in my lap—and he called for a basin. He then slumped into my lap, and I did not realize he had died. So when could he have appointed him?'