When the ark was placed in Solomon's temple, what was inside it?

Answer: Only the two stone tablets

1 Kings 8:9 says there was nothing in the ark except the two stone tablets Moses had placed in it at Horeb.

“There was nothing in the ark except the two stone tablets that Moses had placed in it at Horeb, where the LORD had made a covenant with the Israelites after they had come out of the land of Egypt.”— 1 Kings 8:9 (BSB)