Musnad Ahmad 1168:0

Narrated by Umm Qays bint Mihsan, the sister of Ukashah ibn Mihsan: She came to the Messenger of Allah (ﷺ) with a son of hers who had not yet begun to eat food. She placed him in the lap of the Messenger of Allah (ﷺ), and he urinated on his garment. The Messenger of Allah (ﷺ) called for water and sprinkled it over the spot, but he did not wash it. She also narrated that she entered upon the Messenger of Allah (ﷺ) with a son of hers who had not yet reached the age of eating food, and he had not yet begun to eat. She brought him to the Messenger of Allah (ﷺ), and he sat him in his lap. The boy urinated on his garment, so he called for water and sprinkled it over it, and he did not wash it.