Musnad Ahmad 1153:2304

Ya'qub narrated to us, he said: My father narrated to us, from his father, that he heard 'Urwah ibn al-Zubayr saying: 'Aishah said: The Messenger of Allah, may Allah bless him and grant him peace, said during his illness: "Command Abu Bakr to lead the people in prayer." She said: So I said: "O Messenger of Allah, Abu Bakr is a tender-hearted man, and if he stands in your place of prayer, he will weep. So command 'Umar ibn al-Khattab to lead them in prayer." She said: He said: "Desist. Command Abu Bakr to lead the people in prayer." She said: So I repeated it to him. He said: "Desist. Command Abu Bakr to lead the people in prayer." She said: So I repeated it to him, and he said: "Command Abu Bakr to lead the prayer; you are indeed the companions of Yusuf."