Musnad Ahmad 1153:1753

'Abd al-Quddus ibn Bakr ibn Khunays narrated to us, he said: Hisham informed us, from his father, from 'Aishah, she said: The Messenger of Allah, may Allah bless him and grant him peace, used to have children brought to him, so he would perform *tahnik* (chew a date and rub it on the palate) for them and invoke blessings upon them. A child urinated in his lap, so he called for water and made the water follow the urine.