Musannaf Ibn Abi Shayba 21:730

Mu'tamir ibn Sulayman narrated to us, from his father, from Husayn, from Ibrahim al-Taymi, who said: When the deceased is placed in the grave, say: "In the name of Allah, and to Allah, and upon the Sunnah of the Messenger of Allah, may Allah bless him and grant him peace."