Musnad Ahmad 32:1015

Muhammad ibn Abdullah narrated to us, Humayd narrated to us, from Anas, that Umm Sulaym gave birth to a boy from Abu Talhah. She sent him with her son Anas to the Messenger of Allah, may Allah bless him and grant him peace, and he performed *tahnik* (chewed a date and rubbed it on the palate) for him.