Aishah and Umm Salamah both reported that the Messenger of Allah ﷺ would wake up in a state of major ritual impurity. Abdullah al-Adhrami added in his narration, "during Ramadan, from sexual relations rather than a wet dream," and then he would fast.
حدثنا القعنبي عن مالك ح و حدثنا عبد الله بن محمد بن إسحق الأذرمي حدثنا عبد الرحمن بن مهدي عن مالك عن عبد ربه بن سعيد عن أبي بكر بن عبد الرحمن بن الحارث بن هشام
أنهما قالتا كان رسول الله ﷺ يصبح جنبا قال عبد الله الأذرمي في حديثه في رمضان من جماع غير احتلام ثم يصوم
Muslim narrated it in the Book of Fasting, chapter on the validity of the fast of one who reaches Fajr in a state of major impurity, hadith no. 78/1109, from the hadith of Malik through this same chain, and it is found in Muwatta (Yahya) 289/10, 290. The hadith also has another version narrated by Bukhari, hadith no. 1925, 1926. Hadith no.