It is narrated from Sayyiduna Ali (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said regarding an infant boy: "Sprinkling water over the urine of a boy is sufficient, and if a girl's urine gets on something, it should be washed." Qatadah (may Allah have mercy on him) says that this ruling is until they begin to eat and drink, and when they start eating and drinking, then if the urine of either gets on something, it must be washed.