I think he was from Hijaz. He heard Abdullah bin Jafar telling Ibn Zubayr, while a camel had been slaughtered for the people, that he heard the Messenger of Allah ﷺ say, as the people were placing pieces of meat before the Messenger of Allah ﷺ, "The best meat is the meat of the back."
حدثنا يحيى حدثنا مسعر حدثني شيخ من فهم قال وأظنه يسمى
وأظنه حجازيا أنه سمع عبد الله بن جعفر يحدث ابن الزبير وقد نحرت للقوم جزور أو بعير أنه سمع رسول الله ﷺ والقوم يلقون لرسول الله ﷺ اللحم يقول أطيب اللحم لحم الظهر