It is narrated from Abd al-Rahman bin al-Harith bin Hisham (may Allah have mercy on him) that Marwan bin al-Hakam sent him to Sayyidah Umm Salamah (may Allah be pleased with her). He said: I met her servant Nafi' and sent him to her; he asked her, then he came back to him (Abd al-Rahman) and informed him that she had told him that the Messenger of Allah (peace and blessings be upon him) would reach the morning in a state of major ritual impurity (janabah) due to intercourse, not from a wet dream, and then would continue the morning fasting.
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20217