It was narrated from Umm Qais bin Mihsan that she brought a small son of hers who has not started eating food to the Messenger of Allah (ﷺ). The Messenger of Allah (ﷺ) took him in his lap and he urinated on his garment, so he called for some water and sprinkled it on it, but he did not wash it.
English reference: Vol. 1, Book 1, Hadith 303
Arabic reference: Book 1, Hadith 304