Albert Barnes on Acts 26:17

Delivering thee from the people. From the Jewish people. This implied that he would be persecuted by them, and that the Lord Jesus would interpose to rescue him.

And from the Gentiles. This also implied that he would be persecuted and opposed by them ---a prospect which was verified by the whole course of his ministry. Yet in all he experienced, according to the promise, the support and the protection of the Lord Jesus. This was expressed in a summary manner in Lk 9:16.

Unto whom now I send thee. Acts 22:21. As the opposition of the Jews arose mainly from the fact that he had gone among the Gentiles, it was important to bring this part of his commission into full view before Agrippa, and to show that the same Saviour who had miraculously converted him, had commanded him to go and preach to them.

(a) "unto whom" Acts 22:21, Rom 11:13