Musnad Ahmad 28:344

Waki’ narrated to us, Usamah ibn Zayd narrated to us, from ‘Amr ibn Shu’ayb, from his father, from his grandfather: That the Prophet, peace and blessings of Allah be upon him, found a date under his side during the night, so he ate it. He did not sleep that night. Some of his wives said: "O Messenger of Allah, were you restless last night?" He said: "I found a date under my side, so I ate it, and we had dates from the dates of charity, and I feared that it might be from them."