Rom. 4:1-25 Paul explains how Abraham, the father of the Jewish people, moved from Mesopotamia to Canaan (Palestine) because he had faith in God’s promise (see Genesis 12:1-3). In the same way, any believer – Jew or Gentile – can be forgiven and receive God’s blessings through their faith that Jesus died for their sins and rose again from the dead.
Abraham moved from Harran to become "the father of many nations" (Glumik)
It was because of Abraham’s faith that God promised to make him ‘the father of many nations’, not because he had been circumcised or performed the ‘works’ laid down in the Jewish law. In the same way, God will continue to be faithful to his covenant promise to Abraham by including Gentiles as well as Jews in a single, united, worldwide family.
You can read more about God's promise to Abraham in the Old Testament (Genesis 17:1-27) at The birth of Ishmael.