All the firstborn males that come of your herd and of your flock you shall sanctify unto the LORD your God: you shall do no work with the firstborn of your bullock, nor shear the firstborn of your sheep.

If a man has two wives, one beloved, and another hated, and they have borne him children, both the beloved and the hated; and if the firstborn son be hers that was hated:

Then it shall be, when he makes his sons to inherit that which he has, that he may not make the son of the beloved firstborn before the son of the hated, who is indeed the firstborn:

But he shall acknowledge the son of the hated as the firstborn, by giving him a double portion of all that he has: for he is the beginning of his strength; the right of the firstborn is his.

And it shall be, that the firstborn that she bears shall succeed in the name of his brother who is dead, that his name be not put out of Israel.