Muwatta Imam Malik Book of Purity, Hadith 79

Yahya related to me from Malik from Hisham ibn Urwa from his father that A'isha, the wife of the Prophet ﷺ 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."

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ، زَوْجِ النَّبِيِّ ﷺ أَنَّهَا كَانَتْ تَقُولُ إِذَا أَصَابَ أَحَدُكُمُ الْمَرْأَةَ ثُمَّ أَرَادَ أَنْ يَنَامَ قَبْلَ أَنْ يَغْتَسِلَ فَلاَ يَنَمْ حَتَّى يَتَوَضَّأَ وُضُوءَهُ لِلصَّلاَةِ .