It is narrated from Sayyidah Umm Qays bint Mihsan (may Allah be pleased with her) that she brought a small son of hers, who did not yet eat food, to the Messenger of Allah (peace and blessings be upon him), and the Messenger of Allah (peace and blessings be upon him) seated him in his lap, and he urinated on him (peace and blessings be upon him). The Messenger of Allah (peace and blessings be upon him) called for water, sprinkled it over it, and did not wash it.
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 21901