Abu Jandal and Abu Basir, instructing them to come to him together with whatever Muslims were with them.

The Messenger of Allah’s ﷺ letter reached Abu Jandal while Abu Basir was at the point of death. He died with the Prophet’s letter in his hand, reading it. Abu Jandal buried him where he passed away, performed the funeral prayer for him, and built a mosque over his grave.

I say: You can see that this entire report revolves around al-Zuhri. On the premise that he was a young Successor who heard from Anas ibn Mālik (may Allah be pleased with him), the chain is mursal; otherwise it is muʿḍal. In either case no legal proof can be derived from it, for the very sentence cited as evidence—“and he built a mosque over his grave”—does not appear, in Ibn ʿAbd al-Barr’s presentation of the story, to come from al-Zuhri’s mursal, nor from the transmission of ʿAbd al-Razzāq from Maʿmar on his authority. Rather, it occurs only in the narration of Mūsā ibn ʿUqba, as Ibn ʿAbd al-Barr explicitly stated and did not go beyond. Mūsā ibn ʿUqba did not hear any Companion, so this addition—I mean the words “and he built a mosque over his grave”—is muʿḍal. (1)