What people say is spoken of as being in their mouth. Alternate translation: "He always curses people, tells lies, and threatens to harm people" (See: [[rc://en/ta/man/translate/figs-metonymy]])
Here the tongue represents speaking. Alternate translation: or "what he says injures and destroys people" or "he speaks words that threaten and hurt people" (See: [[rc://en/ta/man/translate/figs-metonymy]])