Sahih al-Bukhari, Volume 1, Book 5, Hadith 285 (USC-MSA) ⓘ
Narrated `Umar bin Al-Khattab: I asked Allah's Messenger "Can any one of us sleep while he is Junub?" He replied, "Yes, if he performs ablution, he can sleep while he is Junub."
حَدَّثَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا اللَّيْثُ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، أَنَّ عُمَرَ بْنَ الْخَطَّابِ، سَأَلَ رَسُولَ اللَّهِ صلى الله عليه وسلم أَيَرْقُدُ أَحَدُنَا وَهْوَ جُنُبٌ قَالَ " نَعَمْ إِذَا تَوَضَّأَ أَحَدُكُمْ فَلْيَرْقُدْ وَهُوَ جُنُبٌ " .
also referenced under: Book 5, Hadith 39 (In-Book) & Hadith 287 (DarusSalam)