Albert Barnes on Acts 13:47

For so, etc. Paul, as usual, appeals to the Scriptures in order to justify his course. He here appeals to the Old Testament, rather than to the command of the Saviour, because the Jews recognized the authority of their own Scriptures, while they would have turned in scorn from the command of Jesus of Nazareth.

I have set thee, etc. I have constituted or appointed thee. This passage is found in Isa 49:6. That it refers to the Messiah there can be no doubt. From the fortieth chapter of Isaiah to the end of the prophecies, Isaiah had a primary and main reference to the times of the Messiah.

To be a light. Jn 1:4.

Of the Gentiles. This was in accordance with the uniform doctrines of Isaiah, Isa 42:1, 44:3, 60:3,5,16, 61:6,9, 62:2, 66:12. Comp. Rom 15:9-12.

For salvation. To save sinners. Unto the ends of the earth, To all lands; in all nations. Acts 1:8.

(e) "saying" Isa 49:6