"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.'"  

ذَكَرَ عُمَرُ لِرَسُولِ اللَّهِ ﷺ أَنَّهُ تُصِيبُهُ الْجَنَابَةُ مِنَ اللَّيْلِ فَقَالَ رَسُولُ اللَّهِ ﷺ تَوَضَّأْ وَاغْسِلْ ذَكَرَكَ ثُمَّ نَمْ