Albert Barnes on Acts 15:12

Then all the multitude. Evidently the multitude of private Christians who were assembled on this occasion. That it does not refer to a synod of ministers and elders merely, is apparent,

(1.) because the church, the brethren, are represented as having been present, and concurring in the final opinion, Acts 15:22,23; and,

(2.) because the word multitude (τοπληθος) would not have been used in describing the collection of apostles and elders merely. Comp. Lk 1:10,11,13, 5:6, 6:17, 19:37, Jn 5:3, 21:6, Acts 4:32, 6:2, Mt 3:7.

Gave audience. Heard; listened attentively to.

Barnabas and Paul. They were deeply interested in it; and they were qualified to give a fair statement of the facts as they had occurred.

Declaring what miracles and wonders, etc. The argument here evidently is, that God had approved their work by miracles; that he gave evidence that what they did had his approbation; and that as all this was done without imposing on them the rites of the Jews, so it would follow that those were not now to be commanded.

(*) "audience" "hearkened to" (d) "God had wrought" Acts 14:27