Musnad Ahmad 27:541

'Abd al-Wahid—meaning al-Haddad—narrated to us, Hammam narrated to us, from Qatadah, from Abu al-Siddiq al-Naji, from Ibn 'Umar, that the Prophet, peace and blessings of Allah be upon him, said: "When you place your dead in the graves, say: 'In the name of Allah, and upon the religion of the Messenger of Allah, peace and blessings of Allah be upon him.'"