Musannaf Ibn Abi Shayba 1:873

Ibn Idris narrated to us, from Hisham, from al-Hasan, that he used to see no harm in a man having intercourse with his wife and then returning [to it] before he performs ablution. He said: And Ibn Sirin used to say, "I do not know of any harm in that." He said: "It was only said that because it is more likely that he will return [to it]."