Genesis 26:4
And I will make thy seed to multiply as the stars of heaven, and will give unto thy seed all these countries; and in thy seed shall all the nations of the earth be blessed; And I will make thy seed to multiply as the stars of heaven, and will give unto thy seed all these countries; and in thy seed shall all the nations of the earth be blessed;
God repeated to Isaac the blessings first given to Abraham because of obedience. The pledge to make Isaac's descendants many, to give them lands, and to bless all nations through his offspring was earned by Abraham's obedience. He promised to multiply Isaac's seed as the stars of heaven, to be countless. That countless number promised to the chosen people is also described as the dust of the earth and as the sand on the seashore, as well as the stars of heaven.
He also promised to give to the seed all these countries, and to bless all the nations of the earth in the seed. The whole promise rests on Abraham obeying God's voice and keeping His charge, His commandments, His statutes, and His laws. This proves that knowledge of God's law was preserved from Adam to Noah, and from Noah to Abraham, and from Abraham to Moses, for the benefit of all who should live upon the earth. It shows God's law was known and obeyed long before Moses.
Abraham is presented as the father of the faithful, whose moral greatness lay in being true to principle and in having unlimited faith in God and in His providential dealings with the faithful.