Servants of God were sometimes adjured by one in authority, and they told the truth. Likewise a Christian under oath would not lie but would tell the whole truth called for, or he may refuse to answer if it jeopardizes the righteous interests of God or of fellow Christians, in which case he must be ready to suffer any consequences that might result from his refusal to testify.​—1Ki 22:15-18; Mt 26:63, 64; 27:11-14.

Jesus Christ, in his Sermon on the Mount, corrected the Jews in their practice of light, loose, and indiscriminate making of oaths. It had become common among them to swear by heaven, by the earth, by Jerusalem, and even by their own heads. But since heaven was “God’s throne,” earth his “footstool,” Jerusalem his kingly city, and one’s head (or life) was dependent on God, making such oaths was the same as taking oaths in the name of God. It was not to be treated lightly. So Jesus said: “Just let your word Yes mean Yes, your No, No; for what is in excess of these is from the wicked one.”​—Mt 5:33-37.

Jesus Christ did not hereby prohibit the making of all oaths, for he himself was under the Law of Moses, which required oaths under certain circumstances. In fact, when Jesus himself was on trial he was put under oath by the high priest, yet he did not object to this, but gave an answer. (Mt 26:63, 64) Rather, Jesus was showing that a person should not have two standards. The keeping of one’s word, once given, should be viewed as a sacred duty and should be fulfilled just as an oath would be; the person should sincerely mean what he says. He shed further light on the meaning of his words when he exposed the hypocrisy of the scribes and Pharisees by saying to them: “Woe to you, blind guides, who say, ‘If anyone swears by the temple, it is nothing; but if anyone swears by the gold of the temple, he is under obligation.’ Fools and blind ones! Which, in fact, is greater, the gold or the temple that has sanctified the gold?” He went on to say: “He that swears by heaven is swearing by the throne of God and by him that is sitting on it.”​—Mt 23:16-22.

By the false reasoning and hairsplitting casuistry of these scribes and Pharisees, as here pointed out by Jesus, they justified themselves in failing to carry out certain oaths, but Jesus showed that such swearing on their part was being dishonest with God and was actually reproaching his name (for the Jews were a people dedicated to Jehovah). Jehovah plainly states that he hates a false oath.​—Zec 8:17.

James corroborates Jesus’ words. (Jas 5:12) But these statements of Jesus and James against such indiscriminate practices do not prevent the Christian from taking an oath when necessary to assure others of the seriousness of his intentions or of the truthfulness of what he says. For instance, as Jesus illustrated by example before the Jewish high priest, a Christian would not object to taking an oath in court, for he is going to speak the truth whether under oath or not. (Mt 26:63, 64) Even the Christian resolve to serve God is an oath or a swearing to Jehovah, putting the Christian into a sacred relationship. Jesus put swearing and vows in the same category.​—Mt 5:33.