Muwatta Imam Malik Book of Purity, Hadith 111

Yahya related to me from Malik from Hisham ibn Urwa from his father that A'isha, the wife of the Prophet ﷺ said, "An infant boy was brought to the Messenger of Allah ﷺ and it urinated on him. The Messenger of Allah ﷺ called for some water and rubbed over the urine with it."

حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ، زَوْجِ النَّبِيِّ ﷺ أَنَّهَا قَالَتْ أُتِيَ رَسُولُ اللَّهِ ﷺ بِصَبِيٍّ فَبَالَ عَلَى ثَوْبِهِ فَدَعَا رَسُولُ اللَّهِ ﷺ بِمَاءٍ فَأَتْبَعَهُ إِيَّاهُ .