2 Chronicles 11:23

11:23 He wisely placed some of his many sons throughout the regions of Judah and Benjamin in the various fortified cities. He supplied them with abundant provisions and acquired many wives for them.

Genesis 25:6

25:6 But while he was still alive, Abraham gave gifts to the sons of his concubines and sent them off to the east, away from his son Isaac.

Deuteronomy 21:15-17

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. 21:16 In the day he divides his inheritance he must not appoint as firstborn the son of the favorite wife in place of the other wife’s son who is actually the firstborn. 21:17 Rather, he must acknowledge the son of the less loved wife as firstborn and give him the double portion of all he has, for that son is the beginning of his father’s procreative power – to him should go the right of the firstborn.