Musnad Ahmad 31:672

Abu Sa’id, the freed slave of Banu Hashim, narrated to us, saying: ‘Abd al-Rahman ibn Abi al-Mawali—a freed slave of the family of ‘Ali—narrated to us, saying: ‘Abd al-Rahman ibn Abi ‘Amrah narrated to us, saying: There was a funeral in the Hijr, and Abu Sa’id came, so they made space for him. But he refused to move forward and said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "Indeed, the best of gatherings are the most spacious of them."