Sahih Bukhari Volume 1, Book 12, Hadith Number 816

Narated By Sulaiman Ash-Shaibam : I heard Ash-Sha’bi saying, “A person who was accompanying the Prophet passed by a grave that was separated from the other graves told me that the Prophet once led the people in the (funeral) prayer and the people had aligned behind him. I said, “O Aba ‘Amr! Who told you about it?” He said, “Ibn Abbas.”