Sahih Muslim , Book 2, Hadith 125 (In-Book) ⓘ

Anas reported: A Bedouin urinated in the mosque. Some of the persons stood up (to reprimand him or to check him from doing so), but the Messenger of Allah said: Leave him alone; don't interrupt him. He (the narrator) said: And when he had finished, he called for a bucket of water and poured it over.

وَحَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا حَمَّادٌ، - وَهُوَ ابْنُ زَيْدٍ - عَنْ ثَابِتٍ، عَنْ أَنَسٍ، أَنَّ أَعْرَابِيًّا، بَالَ فِي الْمَسْجِدِ فَقَامَ إِلَيْهِ بَعْضُ الْقَوْمِ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ دَعُوهُ وَلاَ تُزْرِمُوهُ ‏" ‏ ‏.‏ قَالَ فَلَمَّا فَرَغَ دَعَا بِدَلْوٍ مِنْ مَاءٍ فَصَبَّهُ عَلَيْهِ ‏.‏