All his fellows; or, all its associates'; i.e. all who are associated together in the worship of the idol. The worshippers of a particular idol, or sometimes of a particular god, formed a sort of guild or company, bound together by common participation in certain rites, and under an obligation to defend each other.
The prophet says that, though the worshippers and the makers should, all of them, be gathered together, and stand up to help one the ether, yet should they be unable to effect anything. Gathered together against God, they would "tremble and be ashamed."