It was not the intention of Jesus to repeal or abolish this law. God's Law allowed, and in some instances required, the administration of an oath made unto the Lord (Exodus 22:11, Numbers 5:19). But the Jews, looking upon this law, construed it as giving them exemption from the binding effect of all other oaths. According to their construction, no oath was binding in which the name of God did not directly occur. They therefore coined many other oaths to suit their purposes, which would add weight to their statements or promises, which, however, would not leave them guilty of being forsworn if they spoke untruthfully.
But Jesus showed that all oaths were ultimately referable to God, and that those who made them would be forsworn if they did not keep them. To prevent this evil practice of loose swearing Jesus lays down the prohibition, "Swear not at all."
Christ does not forbid judicial oaths in this prohibition. This conclusion is also reached when we interpret the prohibition in the light of authoritative examples; for we find that God swore by himself (Genesis 22:16-17; Hebrews 6:13; 7:21); Jesus answered under oath before the Sanhedrin (Matthew 26:63); Paul also made an oath to the Corinthian church (2 Corinthians 1:23) and made solemn appeals to God (Romans 1:9, Galatians 1:20, Philippians 1:8; 1 Corinthians 15:31, 1 Thessalonians 5:27, Revelation 10:5-6).
Therefore, judicial oaths, and oaths taken in the name of God on occasions of solemn religious importance, are not included in the prohibition. But as these are the only exceptions found in Scriptures, we conclude that all other oaths are forbidden. Looking at the details of the paragraph, we find that oaths "by heaven...by the earth...by Jerusalem...and by thy head" are utterly meaningless save as they have reference to God.
Jesus says elsewhere that all who swear at all, do in fact swear by God, or the oath is good for nothing (Matthew 23:22). To swear by an altar, a gift, or a temple, is of no force, unless it be meant to appeal to God himself. The essential thing in an oath is calling God to witness our sincerity. If a real oath is taken, therefore, God is appealed to. If not, it is foolish and wicked to swear by anything else.
Another example is when Jesus said:
Matthew 5:31-32, "It hath been said, Whosoever shall put away his wife, let him give her a writing of divorcement: But I say unto you, That whosoever shall put away his wife, saving for the cause of fornication, causeth her to commit adultery:"
Did Jesus teach something new?
The Pharisees are the ones who said that it was "...lawful for a man to put away his wife for every cause" (Matthew 19:3), And Jesus was correcting them by saying, in Matthew 19:8, "...but from the beginning it was not so.” Some may claim that Jesus was changing the law of Moses which permitted divorce (Deuteronomy 24:1-4). However, when one reads the law of divorce carefully, it tells us that when the woman divorces and remarries another, she will be defiled. The only thing removed was the curse of the law, but the law that said she would be defiled if she married another man did not change. It was still a sin, but God permitted that evil, temporarily, to prevent an even greater evil. It was still God's will, in Moses' time, that divorce not happen, and it was still a sin.
Deuteronomy 24:4, "the former husband who sent her away shall not be able to return and take her to himself for a wife, after she has been defiled."
Jesus was simply teaching the same law that was from the beginning! Jesus taught nothing new!
Another example is when Jesus said:
Matthew 5:38-39, "Ye have heard that it hath been said, An eye for an eye, and a tooth for a tooth: But I say unto you…"
Did Jesus teach something new?
Jesus was not saying that the Old Testament law on an eye for an eye has now passed away! Because a few minutes earlier he had just stated that none of the Old Testament law would pass away (Matthew 5:17-18), and Jesus would not contradict himself. So, what was Jesus teaching in this passage?
The reference to "an eye for an eye" is found in Exodus 21:24-25, which deals with how the judges (magistrate) must deal with a crime (Deuteronomy 19:18-21 explains how the judges were to carry out this eye for an eye judgment). Namely, the punishment must fit the crime. The religious leaders of Christ's day had twisted a passage that applied to the magistrates and misused it as a principle of personal revenge. Christ is clearing up a confusion that had led people to think that conduct proper for the magistrates—that is, taking vengeance—was also proper for an individual. This law of retribution was designed to take vengeance out of the hands of personal revenge and commit it to the magistrate.
The Pharisees and their followers misused this law as a principle of personal revenge, so that they could give "tit for tat" to those who harmed them, which is contrary to the injunctions of the Old Testament itself (Proverbs 20:22; 24:29). A law that was meant to be a guide to judges rendering judicial decisions and handing down sentences was never meant to be a rule of our personal relationships. The function of magistrates is to administer the vengeance of God upon evil doers (Romans 13:4), but not so with individuals. Our duty is to love our neighbor as the Lord Jesus has instructed us.
Jesus was teaching from the Old Testament, which specifically stated that if evil is done to us, we are not to do to him as he did to us!
Proverbs 24:29, "Say not, I will do so to him as he hath done to me: I will render to the man according to his work."
The reason is because this would be personal revenge. Instead, the duty of rendering to man his evil work is the duty of the majistrates. Jesus taught nothing new.
Another example is when Jesus said:
Matthew 5:27-28, "Ye have heard that it was said by them of old time, Thou shalt not commit adultery: But I say unto you, That whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart."
Was Jesus teaching something new? No, Jesus was not teaching something new. Just as in all the other examples given in Matthew 5 above, Jesus was teaching directly from the Old Testament. The spiritual meanings of the Old Testament laws are also found in the Old Testament itself.
Please read God's seventh and tenth commandments:
7th Commandment: "Thou shalt not commit adultery." (Exodus 20:14).
10th Commandment: "Thou shalt not covet thy neighbour's wife." (Exodus 20:17).
In other words, this 10th Commandment says that whosoever “covets, desires, or lusts” after a married woman, has committed adultery with her already in ones heart!!! Why? Because one has broken the 7th Commandment already in one's heart! This is the spiritual meaning of adultery, and this is exactly what Jesus meant when he spoke in Matthew 5:27-28.