Deuteronomy 21:17

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.

Deuteronomy 30:20

30:20 I also call on you to love the Lord your God, to obey him and be loyal to him, for he gives you life and enables you to live continually in the land the Lord promised to give to your ancestors Abraham, Isaac, and Jacob.”