Jesus had told His disciples not to swear oaths falsely and not to swear frivolously, by invoking heaven, earth, Jerusalem, or one’s own head, as contemporaries did. With these two principles, He puts boundaries on the use of our tongues. On the one hand, we are to avoid falsehood and speak only the truth. As an extreme case, He forbids us to make an affirmation that we know is false. By extension, He forbids also breaking promises we have kept. In other words, our words must be reliable. They must be true and trustworthy. If we state something, it should be accurate. If we make a commitment, we should honor it. Followers of Jesus will keep their marriage vows. They will swear to their own hurt and not change (Psalm 15:4). They will not renege on a contract. They will not undertake obligations lightly, but they will fulfill those they do undertake. On the other hand – and as condition for keeping our word – we are to avoid unnecessary speech. Jesus’ brother James, whose short letter often echoes the Sermon on the Mount, admonished, “Let every man be quick to hear, slow to speak, slow to wrath” (1:19), and pointed out the evils caused by an unbridled tongue. Indeed, he says that “If anyone among you thinks he is religious, and does not bridle his tongue but deceives his own heart, this one’s religion is useless” (1:26). Paul urged the Ephesian Christians, “Let no corrupt word proceed out of your mouth, but what is good for necessary edification [building others up], that it may impart grace to the hearers” (4:29). Healso warned against the dangers of foolish jesting (5:4). Nine hundred years earlier, King Solomon had advised, “Let your words be few” (Ecclesiastes 5:2). More pointedly, he observed that “the fool multiplies words” (10:14)…He who restrains his words has knowledge…Do you see a man who is hasty in his words? There is more hope for a fool than for him” (Proverbs 17:27; 29:20). In sum: Avoid false and frivolous speech, and we shall avoid a great deal of folly.