Muwatta Malik 108
موطأ مالك#108SahihYahya 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
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Salim al-HilaliMauquf Sahih
In-book reference: 2:77