Rom 15:8-12, Mt 12:21, Acts 26:15-18

In the Old Testament, Isaiah prophesied that on that day the nations would return to Christ, the descendant of Jesse. (Isa 11:10-12)

Isa 11:10 And in that day there shall be a root of Jesse, which shall stand for an ensign of the people; to it shall the Gentiles seek: and his rest shall be glorious. 11 And it shall come to pass in that day, that the Lord shall set his hand again the second time to recover the remnant of his people, which shall be left, from Assyria, and from Egypt, and from Pathros, and from Cush, and from Elam, and from Shinar, and from Hamath, and from the islands of the sea. 12 And he shall set up an ensign for the nations, and shall assemble the outcasts of Israel, and gather together the dispersed of Judah from the four corners of the earth.

By being circumcised, Jesus made the Gentiles who believed in him also receive God's mercy. (Romans 15:8-9)

Romans 15:8 Now I say that Jesus Christ was a minister of the circumcision for the truth of God, to confirm the promises made unto the fathers: 9 And that the Gentiles might glorify God for his mercy; as it is written, For this cause I will confess to thee among the Gentiles, and sing unto thy name.

Jesus became the hope of the Gentiles according to the prophecies of the Old Testament. (Mt 12:21)

Mt 12:21 And in his name shall the Gentiles trust.

The resurrected Jesus appeared to Saul and said that he would send Saul to the Gentiles to preach the gospel and bring them back to God. (Acts 26:15-18)

Acts 26:15 And I said, Who art thou, Lord? And he said, I am Jesus whom thou persecutest. 16 But rise, and stand upon thy feet: for I have appeared unto thee for this purpose, to make thee a minister and a witness both of these things which thou hast seen, and of those things in the which I will appear unto thee; 17 Delivering thee from the people, and from the Gentiles, unto whom now I send thee, 18 To open their eyes, and to turn them from darkness to light, and from the power of Satan unto God, that they may receive forgiveness of sins, and inheritance among them which are sanctified by faith that is in me.