The Saviour is first promised in - “I will put enmity between you and the woman, and between your offspring and her offspring; he shall bruise your head, and you shall bruise his heel.” When Adam and Eve broke God’s commandment, God announced judgement on the whole world through them - they were now cut off from His presence. He also announced a judgement on the Devil who tempted them, which was also a gracious promise to mankind: that one day a descendant of Eve would come, and though the devil will injure him, he would ultimately destroy the devil and his works.
In we are introduced to Abraham. God promised him that his descendants would be a great nation, and that through him, “all the families of the earth would be blessed” ( ). That promise was renewed again to Abraham’s son Isaac, and Isaac’s son Jacob.
The Great Commission at the gospel’s end echoes God’s promise to Abraham that “all nations” will be blessed in Abraham’s seed.
Sproul, R. C. (Ed.). (2015). The Reformation Study Bible: English Standard Version (2015 Edition) (p. 1668). Orlando, FL: Reformation Trust.