Musnad Ahmad 1300:1

Abu Bakr al-Hanafi narrated to us, he said: Usamah ibn Zayd narrated to us, from ‘Amr ibn Shu‘ayb, from Umm Kurz al-Khuza‘iyyah, she said: "A boy was brought to the Prophet, peace and blessings of Allah be upon him, and he urinated on him, so he ordered it and it was sprinkled with water. And a girl was brought and she urinated on him, so he ordered it and it was washed."