"Umar mentioned to the Messenger of Allah ﷺ that he became Junub at night, and the Messenger of Allah ﷺ said: 'Perform Wudu' and wash you penis, then sleep.'" (Using translation from Nasāʾī 260)  

ذَكَرَ عُمَرُ لِرَسُولِ اللهِ ﷺ أَنَّهُ تُصِيبُهُ جَنَابَةٌ مِنَ اللَّيْلِ فَقَالَ رَسُولُ اللهِ ﷺ «تَوَضَّأْ وَاغْسِلْ ذَكَرَكَ ثُمَّ نَمْ»