2 Kings 11:6

(a third shall also be at the [city] gate Sur, and a third at the gate behind the guards); so you shall keep watch over the palace [from three posts] for defense.

1 Chronicles 26:13-19

They cast lots, the small (younger) and great (older) alike, in accordance with their fathers’ households, for every gate.

2 Chronicles 23:4-5

This is what you shall do: a third of you, of the priests and Levites who are resuming service on the Sabbath, shall be gatekeepers,

Treasury of Scripture Knowledge

Summary

And a third part shall be at the gate of Sur; and a third part at the gate behind the guard: so shall ye keep the watch of the house, that it be not broken down.

Bible References

The gate of sur

1 Chronicles 26:13
They cast lots, the small (younger) and great (older) alike, in accordance with their fathers’ households, for every gate.
2 Chronicles 23:4
This is what you shall do: a third of you, of the priests and Levites who are resuming service on the Sabbath, shall be gatekeepers,