2 Kings 11:6

(one third also shall be at the gate Sur, and one third at the gate behind the guards), shall keep watch over the house for defense.

1 Chronicles 26:13-19

They cast lots, the small and the great alike, according to their fathers’ households, for every gate.

2 Chronicles 23:4-5

This is the thing which you shall do: one third of you, of the priests and Levites who come in 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 and the great alike, according to their fathers’ households, for every gate.
2 Chronicles 23:4
This is the thing which you shall do: one third of you, of the priests and Levites who come in on the sabbath, shall be gatekeepers,