We cannot but speak; in a moral, not in a physical sense; they could not restrain speaking, because of the necessity which was laid upon them, and the woe which would have befallen them, if they had not preached the gospel, 1 Corinthians 9:16. If any man denies to bear testimony for man to a truth, he sins; how much more does he sin, who forbears to witness for God, and at the command or the sending of God!
Related Commentaries of Acts 4:20
Acts 4:20
20 For we cannot but speak the things which we have seen and heard.