Sahih Bukhari Volume 1, Book 4, Hadith Number 223

Narated By Um Qais bint Mihsin : I brought my young son, who had not started eating (ordinary food) to Allah’s Apostle who took him and made him sit in his lap. The child urinated on the garment of the Prophet, so he asked for water and poured it over the soiled (area) and did not wash it.