A.T. Robertson Commentary Acts 8:11

"And they gave heed to him, because that of long time he had amazed them with his sorceries." — Acts 8:11 (ASV)

Because that of long time he had amazed them with his sorceries (δια το ικανω χρονω ταις μαγιαις εξεστακενα αυτους). Causal use of δια with the accusative articular infinitive (perfect active Koine form and transitive, εξεστακενα). Same verb as in verse 9 participle εξιστανων and in verse 13 imperfect passive εξιστατο (cf. also 2:7 already). Χρονω is associative instrumental and μαγιαις instrumental case.