Ps 141:3-4 Set a guard over my mouth, O Lord; keep watch over the door of my lips. Let not my heart be drawn to what is evil, to take part in wicked deeds with men who are evildoers; let me not eat of their delicacies.
This fits right in with James 3, depicting the tongue as the gateway to our attitude, and our attitude as the gateway to our actions and affections. This is why saying negative stuff is so dangerous. It’s not that it’s magic and something has now been inadvertently cursed. It’s what it does to our attitudes. Like pouring salt on your garden plants – it just kills.