Charles Ellicott Commentary 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 Jehovah." — 2 Chronicles 23:5 (ASV)

And a third part at the gate of the foundation. — 2 Kings 11:6 reads: the gate Sûr, which appears there as a gate of the palace. (Septuagint, the middle gate; Syriac and Arabic, the Butchers’ gate)

And all the people shall be in the courts of the house of the Lord. — This appears to be written from the point of view of a strict legalist, according to which no one was permitted to enter the holy house itself except the priests. It looks like a protest against 2 Kings 11:4, where it is said that Jehoiada brought the centurions of the royal guard into the house of the Lord.