Sunan Ibn Majah, Book 1, Hadith 628 (In-Book) ⓘ
It was narrated from Ibn 'Umar that : 'Umar bin Khattab said to the Messenger of Allah: "can anyone of us sleep if he is sexually impure?" He said: "Yes, if he performs ablution."
حَدَّثَنَا نَصْرُ بْنُ عَلِيٍّ الْجَهْضَمِيُّ، حَدَّثَنَا عَبْدُ الأَعْلَى، حَدَّثَنَا عُبَيْدُ اللَّهِ بْنُ عُمَرَ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، أَنَّ عُمَرَ بْنَ الْخَطَّابِ، قَالَ لِرَسُولِ اللَّهِ ـ صلى الله عليه وسلم ـ أَيَرْقُدُ أَحَدُنَا وَهُوَ جُنُبٌ قَالَ " نَعَمْ إِذَا تَوَضَّأَ " .
also referenced under: Hadith 585 (Reference) & Volume 1, Book 1, Hadith 585 (DarusSalam)