Muwatta Malik 140

Yahya related to me from Malik from Ibn Shihab from Ubaydullah ibn Abdullah ibn Utba ibn Masud from Umm Qays ibn Mihsan that she brought a baby boy of hers who was not yet eating food to the Messenger of Allah, may Allah bless him and grant him peace, and he sat it in his arms and it urinated on his garment, so the Messenger of Allah, may Allah bless him and grant him peace, called for some water and sprinkled over it but did not wash it