Deuteronomy 11:2

11:2 Bear in mind today that I am not speaking to your children who have not personally experienced the judgments of the Lord your God, which revealed his greatness, strength, and power.

Deuteronomy 21:15

Laws Concerning Children

21:15 Suppose a man has two wives, one whom he loves more than the other, and they both bear him sons, with the firstborn being the child of the less loved wife.