Complete Deuteronomy 28:13: "The LORD will make you the head and not the ___."

Answer: tail

If Israel obeyed, they would be the head and not the tail, moving only upward and never downward (Deuteronomy 28:13).

“The LORD will make you the head and not the tail; you will only move upward and never downward, if you hear and carefully follow the commandments of the LORD your God, which I am giving you today.”— Deuteronomy 28:13 (BSB)