Luke
Acts 9:20ESV·traditional attribution

And immediately he proclaimed Jesus in the synagogues, saying, “He is the Son of God.”

John Calvin Reformed @genevareformer

20. Luke declareth now how fruitful Paul’s conversion was, to wit, that he came abroad by and by, “Statim prodient in publicum,” immediately appeared in public. and did not only profess that he was a disciple of Christ, but did also set himself against “Se... objecerit,” exposed himself to. the fury and hatred of the enemies, by defending the gospel stoutly.

Matthew Henry Presbyterian @wholebiblehenry

As for God, his work is perfect; if he begin, he will make an end: a good work was begun in Saul, when he was brought to Christ's feet, in that word, Lord, what wilt thou have me to do? And never did Christ leave any that were brought to that. Though Saul was sadly mortified when he lay three days blind, yet he was not abandoned.

Commenting on Acts 9:10-22

John Gill Reformed Baptist @doctorgill

And straightway he preached Christ in the synagogues,.... The Syriac version adds, "of the Jews"; that is, which were in Damascus, Act 9:2 from whence it appears, that he was immediately, as soon as converted, qualified for the work of preaching the Gospel: nor did he confer with flesh and blood, or stand disputing and debating with himself and carnal reason, what was best for...