Charles Ellicott Commentary 2 Kings 12:9

"But Jehoiada the priest took a chest, and bored a hole in the lid of it, and set it beside the altar, on the right side as one cometh into the house of Jehovah: and the priests that kept the threshold put therein all the money that was brought into the house of Jehovah." — 2 Kings 12:9 (ASV)

But. — And.

Jehoiada the priest took a chest. —By order of the king (2 Chronicles 24:8).

Beside the altar, on the right side as one comes into the house of the Lord. —Chronicles says: in the gate of the house of the Lord outwards. This can hardly refer to the same position. It probably describes where the chest, which became a permanent feature of the sanctuary, stood in the time after the return from the Captivity. The chronicler adds that offerings were asked by proclamation throughout the country, and that the princes and people readily contributed.

Put. —Rather, used to put. The chest was kept locked, and the Levitical doorkeepers received the money from those who offered it, and dropped it at once into the chest. This obviated all suspicion of a possible misapplication of the contributions.