And the angel of the Lord called unto Abraham out of heaven the second time,
And said, That in blessing I will bless thee, and in multiplying I will multiply thy seed as the stars of the heaven, and as the sand which is upon the sea shore; and thy seed shall possess the gate of his enemies;
And in thy seed shall all the nations of the earth be blessed; because thou hast obeyed my voice.

And the Lord appeared unto Isaac, and said, Go not down into Egypt; dwell in the land which I shall tell thee of:
Sojourn in this land, and I will be with thee, and will bless thee; for unto thee, and unto thy seed, I will give all these countries, and I will perform the oath which I sware unto Abraham thy father;
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 Isaac called Jacob, and blessed him, and charged him, and said unto him,
God Almighty bless thee, and make thee fruitful, and multiply thee, that thou mayest be a multitude of people;
And give thee the blessing of Abraham, to thee, and to thy seed with thee; that thou mayest inherit the land wherein thou art a stranger, which God gave unto Abraham.

COMMENTARY

I will multiply thy seed as the stars of the heaven
I will perform the oath which I sware unto Abraham thy father; And I will make thy seed to multiply as the stars of heaven
God Almighty bless thee…and multiply thee…and give thee the blessing of Abraham
When God promised Abraham that his descendants would become as numerous as the stars in heaven, it was already implied that the same promise would apply to his son Isaac. How could Abraham’s descendants increase unless Isaac’s did as well?
And again, it was implicit that Jacob would have the same blessing as well by the same logic. In short, Isaac and Jacob might have thought to themselves “well, that was the promise of my fathers…so I guess by default it is also my promise.”
But that’s not how God works. He does want us to infer His involvement in our lives, or just assume that He is blessing us. He does not want us to receive anything by default. The pattern we see from these patriarchs is that He instead comes to each one of His covenant children and makes His promises to them directly. “Never mind that I made similar promises to others, this is a new promise and I am making it with you.”