Musnad Ahmad 1153:734

Mu'ammal narrated to us, he said: Nafi'—meaning Ibn 'Umar—narrated to us, Ibn Abi Mulaykah narrated to us, from 'Aishah, she said: When the illness of the Prophet, peace and blessings of Allah be upon him, in which he passed away, occurred, he said: "Call Abu Bakr and his son for me, so that he may write, lest someone who is greedy should covet the affair of Abu Bakr, and lest someone who wishes should wish." Then he said: "Allah and the Muslims refuse that," twice. And Mu'ammal said once: "And the believers." 'Aishah said: "So Allah and the Muslims refused," and Mu'ammal said once: "And the believers, except that it should be my father, so it was my father."