The Promise & the Seed
He brought Abram forth abroad, and said, "Look now toward heaven, and count the stars, if thou be able to count them"; and He promised Abram, "So shall thy seed be". And Abram believed YHVH; and He counted Abram's belief in this Promise as righteousness, Gen 15:5-6.
Heb 11:9 By faith Abraham sojourned in the Land of Promise, as in a strange country, dwelling in tents with Isaac and Jacob, the heirs with him of the same Promise.
Abraham, Isaac, and Jacob were heirs of the same promise of a prodigious progeny.
Heb 11:12 Therefore sprang there even of one seed, planted in Sarah, (whose womb was as good as dead), becoming as the stars of the sky in multitude, and as the sand which is by the sea shore innumerable (Gen 15:5-6; 17:4; 26:4-5; 28:3,14).
This promise of a teeming multitude of descendants was the common blessing from the Fathers.
Gen 48:17-19 And when Joseph saw that Jacob laid his right hand upon the head of Ephraim, it displeased him; and he held up his father's hand, to remove it from Ephraim's head unto Manasseh's head. And Joseph said unto his father, "not so, my father; for this is the firstborn; put thy right hand upon his head". And his father refused, and said, "I know it, my son, I know it; he also shall become a nation, and he also shall be great; but truly his younger brother shall be greater than he, and Ephraim's physical seed shall be meloh ha goyim (this Hebrew phrase means: a multitude of nations or the fullness of gentiles. This is the phrase that Paul quotes in Rom 11:25 and calls a "mystery". The mystery is that the gentiles who are returning to the Torah via the Messiah are in-fact, the physical descendants of Jacob)".