Umayr bin Sa'id al-Nakha'i says: I was present with Ali bin Abi Talib (may Allah be pleased with him) when he placed a deceased person in the grave, and he said: "Allahumma abduka ibnu abdika nazala bika wa anta khayru manzulin bihi, wa la na'lamu illa khayran wa anta a'lamu bihi, kana yashhadu an la ilaha illallah wa anna Muhammadan Rasulullah, faghfir lahu dhanbahu wa wassi' lahu fi mudkhalihi" (O Allah, this is Your servant, the son of Your servant; he has come to You, and You are the best of hosts. We know nothing of him but good, and You know him better. He used to bear witness that there is none worthy of worship except You alone and that Muhammad (peace and blessings be upon him) is the Messenger of Allah; so forgive him his sins and make his grave spacious for him).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنائز / 7063