Musnad Ahmad 22:35

Isma'il narrated to us, Ibn 'Awn informed us, from Raja' ibn Haywah, who said: Ya'la ibn 'Uqbah built [a structure] during Ramadan, and he woke up in a state of janabah (major ritual impurity). He met Abu Hurayrah and asked him, and he [Abu Hurayrah] said: "He has broken his fast." He [Ya'la] said: "Should I not fast this day and compensate for it with another day?" He [Abu Hurayrah] said: "He has broken his fast." So he went to Marwan and told him. He [Marwan] sent Abu Bakr ibn 'Abd al-Rahman ibn al-Harith to the Mother of the Believers and asked her. She said: "He [the Prophet] used to wake up among us in a state of janabah, without having had a wet dream, then he would wake up fasting." He returned to Marwan and told him. He [Marwan] said: "Go and meet Abu Hurayrah with it." He [Abu Bakr] said: "Neighbor, neighbor." He [Marwan] said: "I adjure you to go and meet him with it." He said: So he met him and told him. He [Abu Hurayrah] said: "I did not hear it from the Prophet, may Allah bless him and grant him peace; rather, al-Fadl ibn 'Abbas informed me of it." He [Raja'] said: When that was over, I met Raja' and said: "The hadith of Ya'la, who told it to you?" He said: "He told it to me himself."