Sayyiduna Abu Sa'id bin Abu Fadalah Ansari رضي الله عنه, who was among the Companions, narrates this statement of the Prophet صلى الله عليه وسلم: "When Allah Almighty will gather all the first and the last people on the Day about which there is no doubt, a caller will announce: Whoever has associated anyone else in an act which he was supposed to do for Allah Almighty, then let him seek his reward from that other one, for Allah Almighty is the most free of need from shirk (associating partners)."
(Imam Ibn Hibban رحمه الله says:) The correct name of the narrator is Sayyiduna Abu Sa'd bin Abu Fadalah.