Muwatta Malik 642

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ سُمَىٍّ، مَوْلَى أَبِي بَكْرٍ عَنْ أَبِي بَكْرِ بْنِ عَبْدِ الرَّحْمَنِ، عَنْ عَائِشَةَ، وَأُمِّ سَلَمَةَ زَوْجَىِ النَّبِيِّ صلى الله عليه وسلم أَنَّهُمَا قَالَتَا إِنْ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم لَيُصْبِحُ جُنُبًا مِنْ جِمَاعٍ غَيْرِ احْتِلاَمٍ ثُمَّ يَصُومُ ‏.‏

Yahya related to me from Malik from Sumayy, the mawla of Abu Bakr, from Abu Bakr ibn Abd ar-Rahman that A'isha and Umm Salama, the wives of the Prophet, may Allah bless him and grant him peace, said, "The Messengerof Allah, may Allah bless him and grant him peace, used to get up in the morning junub from intercourse, not a dream, and would then fast

Reference

Muwatta Malik 642

In-book

Book 18, Hadith 13