Those who say that the sexually impure should not sleep until he performs ablution like his ablution for prayer
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 " .
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."