Musnad Ahmad 1035:1

'Abdullah narrated to us, my father narrated to me—I heard it alone—Muhammad bin Fudayl narrated to us, from 'Asim bin Kulayb, from his father, from a man of the Ansar, who said: We went out with the Messenger of Allah, peace and blessings of Allah be upon him, for the funeral of a man of the Ansar, and I was a boy with my father. The Messenger of Allah, peace and blessings of Allah be upon him, sat at the edge of the grave, and he began to instruct the gravedigger, saying: "Make it wider from the direction of the head, and make it wider from the direction of the feet, for the sake of a date-palm cluster for him in Paradise."