Musnad Ahmad 1271:2

Sulayman ibn Harb narrated to us, he said: Hammad ibn Zayd narrated to us, from Yahya ibn Sa'id, from Muhammad ibn Yahya ibn Habban, from Anas ibn Malik, who said: Umm Haram bint Milhan narrated to me that the Prophet, peace and blessings of Allah be upon him, took a nap in her house one day. Then the Messenger of Allah, peace and blessings of Allah be upon him, woke up while he was laughing. He then mentioned the meaning of it.