Charles Ellicott Commentary Zechariah 9:11

"As for thee also, because of the blood of thy covenant I have set free thy prisoners from the pit wherein is no water." — Zechariah 9:11 (ASV)

You — i.e., Zion.

By the blood of your covenant. — Compare Exodus 24:3-8.

By means in consideration of.

The pit. — i.e., Babylon.