Zaid b. Arqam used to utter four takbirs (Allah is Most Great) over our dead person (during prayer). He uttered five takbirs on a dead person. So I asked him. He replied: The Messenger of Allah (ﷺ) used to utter those.

Abu Dawud said: I remember the tradition of Ibn al-Muthanna in a more guarded way.
Sunan Abi Dawud Book 21, Hadith 109
← Previous Hadith The Messenger of Allah (ﷺ) passed a grave dug freshly. They arranged a row and uttered four takbirs over it. I asked al-Sha'bi: Who told you ? He replied: A reliable person whom 'Abd Allah b. 'Abbas attended.

Sunan Abi Dawud Book 21, Hadith 108 Next Hadith → I prayed over a dead person along with Ibn 'Abbas. He recited Surat al-Fatihah and he said: This is the Sunnah.

Sunan Abi Dawud Book 21, Hadith 110