Psalms 141:3
Set a guard, O LORD, over my mouth; keep watch at the door of my lips.
General
Psalms 17:3-5
You have tried my heart; You have visited me in the night. You have tested me and found no evil; I have resolved not to sin with my mouth. As for the deeds of men—by the word of Your lips I have avoided the ways of the violent. My steps have held to Your paths; my feet have not slipped.
Psalms 39:1
For the choirmaster. For Jeduthun. A Psalm of David. I said, “I will watch my ways so that I will not sin with my tongue; I will guard my mouth with a muzzle as long as the wicked are present.”
Psalms 71:8
My mouth is filled with Your praise and with Your splendor all day long.
Micah 7:5
Do not rely on a friend; do not trust in a companion. Seal the doors of your mouth from her who lies in your arms.
James 1:26
If anyone considers himself religious and yet does not bridle his tongue, he deceives his heart and his religion is worthless.
James 3:2
We all stumble in many ways. If anyone is never at fault in what he says, he is a perfect man, able to control his whole body.