4, 5. How do some Bible proverbs describe the power of words?

⁴ One important reason to guard our speech is that words have power. Proverbs 15:4 says: “A calm tongue is a tree of life, but twisted speech causes despair.”a Even as water revives a thirsty tree, so the calm speech of a soothing tongue can refresh the spirit of those hearing it. In contrast, the twisted words of a perverse tongue can crush the spirit of others. Indeed, the words we speak have the power to injure or to heal.​—Proverbs 18:21.