Sahih al-Bukhari, Hadith 6002

Narrated `Aisha: The Prophet took a child in his lap for Tahnik (i.e. he chewed a date in his mouth and put its juice in the mouth of the child). The child urinated on him, so he asked for water and poured it over the place of the urine.

حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، حَدَّثَنَا يَحْيَى بْنُ سَعِيدٍ، عَنْ هِشَامٍ، قَالَ أَخْبَرَنِي أَبِي، عَنْ عَائِشَةَ، أَنَّ النَّبِيَّ صلى الله عليه وسلم وَضَعَ صَبِيًّا فِي حِجْرِهِ يُحَنِّكُهُ، فَبَالَ عَلَيْهِ، فَدَعَا بِمَاءٍ فَأَتْبَعَهُ‏.‏

sunnah.com