The Apostle Paul
Galatians 2:12BSB·traditional attribution

For before certain men came from James, he used to eat with the Gentiles. But when they arrived, he began to draw back and separate himself, for fear of those in the circumcision group.

John Calvin Reformed @genevareformer

12. For before that certain persons came. The state of the case is here laid down. For the sake of the Jews, Peter had withdrawn himself from the Gentiles, in order to drive them from the communion of the Church, unless they would relinquish the liberty of the Gospel, and submit to the yoke of the Law.

Matthew Henry Presbyterian @wholebiblehenry

I. From the account which Paul gives of what passed between him and the other apostles at Jerusalem, the Galatians might easily discern both the falseness of what his enemies had insinuated against him and their own folly and weakness in departing from that gospel which he had preached to them.

Commenting on Galatians 2:11-21

John Gill Reformed Baptist @doctorgill

For before that certain came from James,.... The Lord's brother, mentioned before with Cephas and John, who resided at Jerusalem, from whence these persons came; and who are said to come from James, because they came from the place and church where he was, though, it may be, not sent by him, nor with his knowledge.