Charles Ellicott Commentary Acts 15:21

"For Moses from generations of old hath in every city them that preach him, being read in the synagogues every sabbath." — Acts 15:21 (ASV)

For Moses of old time.—Literally, of ancient generations. The conjunction gives the reason for writing to the Gentiles, and giving them these injunctions. The Jews, who heard the Law in their synagogues every Sabbath, did not need instruction. It might be taken for granted that they would adhere to the rules now specified. So, in Acts 15:23, the encyclical letter is addressed exclusively to the brethren of the Gentiles.