2 Kings 11:6

and another third at the gate of Sur, and a third at the gate behind the runners, shall guard the post of the palace alternately.

1 Chronicles 26:13-19

And they cast lots, small and great alike, by their fathers' houses, {for their gates}.

2 Chronicles 23:4-5

This is the thing that you must do: one third of you priests and Levites {coming off duty on the Sabbath} [shall be] gatekeepers at the entrances

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
And they cast lots, small and great alike, by their fathers' houses, {for their gates}.
2 Chronicles 23:4
This is the thing that you must do: one third of you priests and Levites {coming off duty on the Sabbath} [shall be] gatekeepers at the entrances