Muwatta Imam Malik Book of Fasting, Hadith 12

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 ﷺ said, "The Messengerof Allah ﷺ used to get up in the morning junub from intercourse, not a dream, and would then fast."

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