2 Chronicles 23:5

And a third part shall be at the king’s house; and a third part at the gate of the foundation: and all the people shall be in the courts of the house of the Lord.

Cross-reference

2 Kings 11:5 gives the parallel account of assigning a third at the royal palace, directly matching this verse.

2 Kings 11:6 continues with a third at the Sur Gate, parallel to the Foundation Gate assignment here.