Sunan Ibn Majah, Book 1, Hadith 565 (In-Book) ⓘ
It was narrated that 'Aishah said: "A baby boy was brought to the Prophet who then urinated on him. He sprinkled over it with water and did not wash it."
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، وَعَلِيُّ بْنُ مُحَمَّدٍ، قَالاَ حَدَّثَنَا وَكِيعٌ، حَدَّثَنَا هِشَامُ بْنُ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ، قَالَتْ أُتِيَ النَّبِيُّ ـ صلى الله عليه وسلم ـ بِصَبِيٍّ فَبَالَ عَلَيْهِ فَأَتْبَعَهُ الْمَاءَ وَلَمْ يَغْسِلْهُ .
also referenced under: Hadith 523 (Reference) & Volume 1, Book 1, Hadith 523 (DarusSalam)