Yahya related to me from Malik from Hisham ibn Urwa from his
father that A'isha, the wife of the Prophet, may Allah bless him and
grant him peace, used to say, "If you have intercourse with your wife
and then wish to go to sleep before doing ghusl, do not sleep until
you have done wudu as for prayer."
Muwatta Malik Book 2, Hadith 78