Deuteronomy 21:16

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.

Berean Standard Bible
Other translations

King James Version

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

World English Bible

then it shall be, in the day that he causes his sons to inherit that which he has, that he may not give the son of the beloved the rights of the firstborn before the son of the hated, who is the firstborn;

American Standard Version

then it shall be, in the day that he causeth his sons to inherit that which he hath, that he may not make the son of the beloved the first-born before the son of the hated, who is the first-born:

Geneva Bible 1599

Then when the time commeth, that hee appointeth his sonnes to be heires of that which he hath, he may not make the sonne of the beloued first borne before the sonne of the hated, which is the first borne:

Darby Translation

then it shall be, in the day that he maketh his sons to inherit what he hath, that he may not make the son of the beloved firstborn before the son of the hated, who is the firstborn;

Young's Literal Translation

then it hath been, in the day of his causing his sons to inherit that which he hath, he is not able to declare first-born the son of the loved one, in the face of the son of the hated one — the first-born.

Bible in Basic English

Then when he gives his property to his sons for their heritage, he is not to put the son of his loved one in the place of the first son, the son of the hated wife:

In context

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

17Instead, 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.

Read Deuteronomy 21