Deuteronomy 21:15-17 If a man has two wives, one beloved and the other unloved, and both bear him sons, but the unloved wife has the firstborn son,

BSB⁽ⁱ⁾ ¹⁵ If a man has two wives, one beloved and the other unloved, and both bear him sons, but the unloved wife has the firstborn son, ¹⁶ when that man assigns his inheritance to his sons he must not appoint the son of the beloved wife as the firstborn over the son of the unloved wife. ¹⁷ 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.