Lk 4:24-27, 2 Kings 5:14, Isa 43:6-7, Mal 1:11, Mic 4:2, Zech 8:20-23, Mt 8:10-11, Rom 10:9-12
In the Old Testament, Elijah was not welcomed in Israel and went to a widow in the land of Sidon. (1 Kings 17:8-9)
1 Kings 17:8 And the word of the Lord came unto him, saying, 9 Arise, get thee to Zarephath, which belongeth to Zidon, and dwell there: behold, I have commanded a widow woman there to sustain thee.
The prophets were not welcome in Israel and went to the lands of the Gentiles. (Luke 4:24-27)
Luke 4:24 And he said, Verily I say unto you, No prophet is accepted in his own country. 25 But I tell you of a truth, many widows were in Israel in the days of Elias, when the heaven was shut up three years and six months, when great famine was throughout all the land; 26 But unto none of them was Elias sent, save unto Sarepta, a city of Sidon, unto a woman that was a widow. 27 And many lepers were in Israel in the time of Eliseus the prophet; and none of them was cleansed, saving Naaman the Syrian.
In the Old Testament, Elisha was not welcome in Israel and healed Naaman the Syrian who was a leper in the Gentile land. (2 Kings 5:14)
2 Kings 5:14 Then went he down, and dipped himself seven times in Jordan, according to the saying of the man of God: and his flesh came again like unto the flesh of a little child, and he was clean.
The Old Testament prophesied that the gospel would be preached to the Gentiles and that the Gentiles would be saved. (Isa 43:6-7, Mal 1:11, Mic 4:2, Zec 8:20-23)
Isa 43:6 I will say to the north, Give up; and to the south, Keep not back: bring my sons from far, and my daughters from the ends of the earth; 7 Even every one that is called by my name: for I have created him for my glory, I have formed him; yea, I have made him.
Mal 1:11 For from the rising of the sun even unto the going down of the same my name shall be great among the Gentiles; and in every place incense shall be offered unto my name, and a pure offering: for my name shall be great among the heathen, saith the Lord of hosts.
Mic 4:2 And many nations shall come, and say, Come, and let us go up to the mountain of the Lord, and to the house of the God of Jacob; and he will teach us of his ways, and we will walk in his paths: for the law shall go forth of Zion, and the word of the Lord from Jerusalem.
Zec 8:20 Thus saith the Lord of hosts; It shall yet come to pass, that there shall come people, and the inhabitants of many cities: 21 And the inhabitants of one city shall go to another, saying, Let us go speedily to pray before the Lord, and to seek the Lord of hosts: I will go also. 22 Yea, many people and strong nations shall come to seek the Lord of hosts in Jerusalem, and to pray before the Lord. 23 Thus saith the Lord of hosts; In those days it shall come to pass, that ten men shall take hold out of all languages of the nations, even shall take hold of the skirt of him that is a Jew, saying, We will go with you: for we have heard that God is with you.
Gentiles who believed in Jesus as the Christ were saved. (Matthew 8:10-11, Acts 13:48)
Matthew 8:10 When Jesus heard it, he marvelled, and said to them that followed, Verily I say unto you, I have not found so great faith, no, not in Israel. 11 And I say unto you, That many shall come from the east and west, and shall sit down with Abraham, and Isaac, and Jacob, in the kingdom of heaven.
Acts 13:48 And when the Gentiles heard this, they were glad, and glorified the word of the Lord: and as many as were ordained to eternal life believed.