Dangers of the tongue:
Not many of you should become teachers, my brothers and sisters, for you know that we who teach will be judged with greater strictness. For all of us make many mistakes. Anyone who makes no mistakes in speaking is perfect, able to keep the whole body in check with a bridle. If we put bits into the mouths of horses to make them obey us, we guide their whole bodies. Or look at ships: though they are so large that it takes strong winds to drive them, yet they are guided by a very small rudder wherever the will of the pilot directs. So also the tongue is a small member, yet it boasts of great exploits. How great a forest is set ablaze by a small fire! And the tongue is a fire. The tongue is placed among our members as a world of iniquity; it stains the whole body, sets on fire the cycle of nature, and is itself set on fire by hell. For every species of beast and bird, of reptile and sea creature, can be tamed and has been tamed by the human species, but no one can tame the tongue—a restless evil, full of deadly poison. With it we bless the Lord and Father, and with it we curse those who are made in the likeness of God. From the same mouth come blessing and cursing. My brothers and sisters, this ought not to be so. Does a spring pour forth from the same opening both fresh and brackish water? Can a fig tree, my brothers and sisters, yield olives, or a grapevine figs? No more can salt water yield fresh.
James 3:1-12