Musnad Ahmad 31:919

'Affan narrated to us, Wuhaib narrated to us, 'Amr ibn Yahya narrated to us, from Muhammad ibn Yusuf ibn 'Abdullah ibn Salam, from Abu Sa'id al-Khudri, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever comes to a funeral among its people and follows it until he prays over it, then for him is a qirat. And whoever goes along with it, then for him are two qirats like Uhud."