Muwatta Malik 108

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

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

Reference

Muwatta Malik 108

In-book

Book 2, Hadith 77