What does the Bible say about the gospel preached to Abraham?

In Galatians 3:8, it is declared that God preached the gospel unto Abraham, indicating that the promise given to him was a precursor to the full revelation of the gospel through Jesus Christ. God communicated to Abraham that he would be the father of many nations and that all families of the earth would be blessed through his seed. This promise encompasses the theological truths foundational to sovereign grace theology, emphasizing God's sovereign choice and faithfulness throughout history.