Even so the tongue is a little member and boasts great things.
See how great a forest a little fire kindles! And the tongue is a fire, a world of iniquity.
The tongue is so set among our members that it defiles the whole body, and sets on fire the course of nature; and it is set on fire by hell.

For every kind of beast and bird, of reptile and creature of the sea, is tamed and has been tamed by mankind. But no man can tame the tongue. It is an unruly evil, full of deadly poison. With it we bless our God and Father, and with it we curse men, who have been made in the similitude of God. Out of the same mouth proceed blessing and cursing.

My brethren, these things ought not to be so. Does a spring send forth fresh water and bitter from the same opening? Can a fig tree, my brethren, bear olives, or a grapevine bear figs? Thus no spring yields both salt water and fresh.

James 3:5–12