Let no corrupting talk come out of your mouths, but only such as is good for building up, as fits the occasion, that it may give grace to those who hear. Ephesians 4:29.
Set a guard, O Lord, over my mouth; keep watch over the door of my lips! Do not let my heart incline to any evil, to busy myself with wicked deeds in company with men who work iniquity, and let me not eat of their delicacies! Psalm 141:3-4.