In Genesis 15, the Lord finalizes his covenant with Abram. All the promises that God had been making to Abram throughout the years were given their guarantee by God himself. He would not break them, no matter what. And because of that covenant, we as Christians have also received the blessing of Abraham through the death of Christ, the very thing the Lord promised he would do if we broke our end of the covenant.
"Christ redeemed us from the curse of the law by becoming a curse for us—for it is written, 'Cursed is everyone who is hanged on a tree'— so that in Christ Jesus the blessing of Abraham might come to the Gentiles, so that we might receive the promised Spirit through faith." Galatians 3:13-14