Jami` at-Tirmidhi Book 10, Hadith 82
"When he Prophet put the deceased in the grave" He said: And Abu Khalid (one of the narrators) said : "When he placed the deceased in the Lahd" - "He said one time: 'In the Name of Allah, by His command and upon the Millah of the Messenger of Allah.' and one time he said: 'In the Name of Allah, by His command and upon the Sunnah of the Messenger of Allah."