حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنْ يَحْيَى بْنِ سَعِيدٍ، أَنَّهُ قَالَ دَخَلَ أَعْرَابِيٌّ الْمَسْجِدَ فَكَشَفَ عَنْ فَرْجِهِ لِيَبُولَ فَصَاحَ النَّاسُ بِهِ حَتَّى عَلاَ الصَّوْتُ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ اتْرُكُوهُ ‏"‏ ‏.‏ فَتَرَكُوهُ فَبَالَ ثُمَّ أَمَرَ رَسُولُ اللَّهِ صلى الله عليه وسلم بِذَنُوبٍ مِنْ مَاءٍ فَصُبَّ عَلَى ذَلِكَ الْمَكَانِ ‏.‏

Yahya related to me from Malik that Yahya ibn Said said, "ABedouin came into the mosque and uncovered his private parts tourinate. The people called out to him and began to raise their voicesbut the Messenger of Allah, may Allah bless him and grant him peace,said ,'Let him be. 'So they let him be and he urinated. Then theMessenger of Allah, may Allah bless him and grant him peace, ordered abucketful of water to be brought and it was poured on the place." Translation Not Available

Book Ref: Muwatta Imam Malik Book 2 Hadith 142
Web Ref:  Muwatta Imam Malik Book 2 Hadith 113