أَخْبَرَنَا سُوَيْدُ بْنُ نَصْرٍ، قَالَ أَنْبَأَنَا عَبْدُ اللَّهِ، عَنْ يَحْيَى بْنِ سَعِيدٍ، قَالَ سَمِعْتُ أَنَسًا، يَقُولُ جَاءَ أَعْرَابِيٌّ إِلَى الْمَسْجِدِ فَبَالَ فَصَاحَ بِهِ النَّاسُ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ اتْرُكُوهُ ‏"‏ ‏.‏ فَتَرَكُوهُ حَتَّى بَالَ ثُمَّ أَمَرَ بِدَلْوٍ فَصُبَّ عَلَيْهِ ‏.‏

Anas said: "A Bedouin came to the Masjid and urinated, and the people yelled at him, but the Messenger of Allah (PBUH) said: 'Leave him alone.' So they left him alone. When he had finished urinating, he ordered that a bucket (be brought) and poured over it." Translation Not Available

Book Ref: Sunan An Nisai Book 1 Hadith 55
Web Ref:  Sunan An Nisai Vol 1 Book 1 Hadith 55