Instead, he must acknowledge the firstborn, the son of his unloved wife, by giving him a double portion of all that he has. For that son is the firstfruits of his father’s strength; the right of the firstborn belongs to him.
Reuben, you are my firstborn, my might, and the beginning of my strength, excelling in honor, excelling in power.
“First sell me your birthright,” Jacob replied.
These were the sons of Reuben the firstborn of Israel. Though he was the firstborn, his birthright was given to the sons
Then He struck all the firstborn in their land, the firstfruits of all their vigor.
Abraham left everything he owned to Isaac.