'Covenant' in the Bible

You are the sons (descendants) of the prophets and [heirs] of the covenant which God made with your fathers, saying to Abraham, ‘And in your seed (descendant) all the families of the earth shall be blessed.’

And God gave Abraham a covenant [a formal agreement to be strictly observed] of [which] circumcision [was the sign]; and so [under these circumstances] Abraham became the father of Isaac, and circumcised him on the eighth day; and Isaac [became the father] of Jacob, and Jacob [became the father] of the twelve patriarchs.