Acts 22:8

1. But again, we allege the same against those who do not recognise Paul as an apostle: that they should either reject the other words of the Gospel which we have come to know through Luke alone, and not make use of them; or else, if they do receive all these, they must necessarily admit also that testimony concerning Paul, when he (Luke) tells us that the Lord spoke at first to him from heaven: “Saul, Saul, why persecutest thou Me? I am Jesus Christ, whom thou persecutest;” and then to Ananias, saying regarding him: “Go thy way; for he is a chosen vessel unto Me, to bear My name among the Gentiles, and kings, and the children of Israel. …

This testimony is incontrovertible; the (unbelief) of the Jews (is left) without excuse. See how many witnesses he brings forward, the elders, the high-priest, and those in the city. Observe his defence, how it is not of cowardly fear (for himself, that he pleads), no, but for teaching and indoctrination. For had not the hearers been stones, they would have felt the force of what he was saying. For up to this point he had themselves as witnesses: the rest, however, was without witnesses: “From whom also I received letters unto the brethren, and went to Damascus, to bring them which were there bound unto Jerusalem, for to be punished. And it came to pass, that, as I made my journey, and was come nigh unto Damascus about noon, suddenly there shone from heaven a great light round about me. …

For hence it is that it is said to Jeremiah when sent to preach, See, I have this day set thee over the nations and over the kingdoms, to pluck out, and to pull down, and to destroy, and to scatter, and to build, and to plant ( Jer. i. 10 ). Because, unless he first destroyed wrong things, he could not profitably build right things; unless he plucked out of the hearts of his hearers the thorns of vain love, he would certainly plant to no purpose the words of holy preaching. …