Musnad Ahmad 1153:1655

Yahya narrated to us, from Ibn Jurayj, who said: Abd al-Malik ibn Abi Bakr ibn Abd al-Rahman ibn al-Harith ibn Hisham narrated to me, from his father, that he heard Abu Hurayrah saying: "Whoever wakes up in a state of janabah (major ritual impurity), let him not fast." He said: So Abu Bakr and his father Abd al-Rahman set out until they entered upon Umm Salamah and Aisha. Both of them said: "The Messenger of Allah (peace and blessings of Allah be upon him) used to wake up in a state of janabah without having had a wet dream, and then he would fast." So Abu Bakr and his father Abd al-Rahman set out and came to Marwan and told him. He said: "I adjure you both, when you go to Abu Hurayrah, to tell him." So they went to Abu Hurayrah and informed him. He said: "Did they both say that to you?" They said: "Yes." He said: "They are more knowledgeable. I was only informed of it by al-Fadl ibn Abbas."