The Book of Fasting
13/13. Chapter:
The fasting is valid for the one who is Junub when dawn comes
Sahih Muslim
حَدَّثَنَا أَحْمَدُ بْنُ عُثْمَانَ النَّوْفَلِيُّ، حَدَّثَنَا أَبُو عَاصِمٍ، حَدَّثَنَا ابْنُ جُرَيْجٍ، أَخْبَرَنِي مُحَمَّدُ بْنُ يُوسُفَ، عَنْ سُلَيْمَانَ بْنِ يَسَارٍ، أَنَّهُ سَأَلَ أُمَّ سَلَمَةَ - رضى الله عنها - عَنِ الرَّجُلِ يُصْبِحُ جُنُبًا أَيَصُومُ قَالَتْ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يُصْبِحُ جُنُبًا مِنْ غَيْرِ احْتِلاَمٍ ثُمَّ يَصُومُ .
Sulaiman b. Yasar reported that he asked Umm Salama whether a person (who gets up) in the morning in a state of junub should observe fast. She said: The Messenger of Allah (ﷺ) (at times) got up in the morning in a state of junub, not because of sexual dreams (but on account of intercourse at night), and then observed fast.
Reference : Sahih Muslim 1109eIn-book reference : Book 13, Hadith 100USC-MSA web (English) reference : Book 6, Hadith 2456