What did God tell Joshua to do to the horses of the kings at the waters of Merom?

Answer: Hamstring them

God promised victory and told Joshua to hamstring the enemy's horses and burn up their chariots.

“All these kings joined forces and encamped at the waters of Merom to fight against Israel. Then the LORD said to Joshua, “Do not be afraid of them, for by this time tomorrow I will deliver all of them slain before Israel. You are to hamstring their horses and burn up their chariots.””— Joshua 11:5-6 (BSB)