Musannaf Ibn Abi Shayba 1:964

Suwayd narrated to us, from ‘Amr, from Hammad ibn Salamah, from Hisham ibn ‘Urwah, from his father, from Abu Ayyub, from Ubayy ibn Ka‘b, from the Prophet (peace and blessings of Allah be upon him), who said: "There is nothing in *al-iksal* (sexual intercourse without ejaculation) except *al-tuhur* (performing ablution)."