Charles Ellicott Commentary 2 Chronicles 5:10

"There was nothing in the ark save the two tables which Moses put [there] at Horeb, when Jehovah made a covenant with the children of Israel, when they came out of Egypt." — 2 Chronicles 5:10 (ASV)

Put therein. —Heb., which Moses put — in Horeb. Kings is fuller and clearer: which Moses placed there in Horeb. The chronicler has substituted “put” for “placed;” perhaps remembering Exodus 40:20: And he put the testimony into the ark. The word shâm, “there” or “therein,” has fallen out of the text.

When the Lord made a covenant. — Which (the two Tables, i.e., the Covenant) the Lord covenanted with the sons of Israel. (Compare 2 Chronicles 6:11: the Ark wherein is the covenant of the Lord, 1 Kings 8:21).