In Matthew 5:33-37, Jesus continues to define the righteousness of his kingdom in the context of personal relationships. In previous verses, He addressed the issues of murder and adultery with their accompanying heart motivations: anger and lust. According to Jesus, true righteousness is not simply avoiding outward expressions of sin such as murder and adultery. True righteousness is doing the hard work of repenting of the sin in our hearts (such as lust and anger), loving what is pleasing to God, and by the power of the Spirit, seeking to live that out in our lives.
In this passage (5:33-37), Jesus transitions from pursuing righteousness in marriage relationships to pursuing righteous speech in all our relationships,
“Again, you have heard that the ancients were told, ‘You shall not make false vows, but shall fulfill your vows to the Lord.’ But I say to you, take no oath at all, neither by heaven, for it is the throne of God, nor by the earth, for it is the footstool of His feet, nor by Jerusalem, for it is the city of the Great King. Nor shall you take an oath by your head, for you cannot make a single hair white or black. But make sure your statement is, ‘Yes, yes’ or ‘No, no’; anything beyond these is of evil origin.”
Why does Jesus address oaths? Because the religious leaders were evading the obligation to be honest through the use of deceptive oath formulas. According to them, oaths were binding only when they invoked the name of the Lord. Thus, they could intentionally swindle someone by saying, “I swear by God’s throne in heaven that I will repay you.” According to their tradition (the phrase quoted is not found in the OT), they only had to fulfill their “vows to the Lord,” (v. 33). Thus, they would not be bound by oaths without this phrase.
Even though the religious leaders’ intentionwas to deceive, they nevertheless maintained their “righteousness” because they were not technically breaking their tradition. If they meant to keep their vow, they would make an oath “to the Lord.” But if they meant to deceive, they would swear by something else: heaven, earth, Jerusalem, or their heads. Thus, they were “righteous” on the outside, but their hearts were full of deceit.
As can be seen with murder and adultery, Jesus is not concerned with outward performance, but with the heart. “God does not see as man sees, since man looks at the outward appearance, but the Lord looks at the heart” (1 Samuel 16:7). In contrast to the hearts of deceit in the religious leaders, the members of Christ’s kingdom have been given new hearts that know and love God’s law (Jeremiah 33:31). They have been given Christ’s righteousness. And they are called to live out that righteousness in their lives, a righteousness that is characterized by loving what is true rather than what is false.
Jesus prohibits oath-taking because it naturally degenerates into dishonesty. When someone swears, they are holding themselves to a higher standard of honesty than they usually do. By contrast, Jesus wants the members of His kingdom to be people of such integrity that they can be trusted without making an oath. They are to be people who love the truth and speak the truth. They have no need for oaths, their yes is always yes and their no is always no.
Why should followers of Jesus love the truth? Because He is the truth (John 14:6). All truth points to and culminates in Him. Loving Jesus leads us to loving the truth. Thus, we should pursue simple truthfulness in our speech. “Anything more than this,” Jesus says, “is from the evil one” (5:37). Satan is the father of lies (John 8:44), the master of persuasive half-truths whose deception led to humanity’s downfall (Gen 3:1-7). Any act of deception displays his deceptive influence. Any act of honesty displays Christ’s sanctifying truth.
Although it is easy to point our fingers at the religious leaders, we stand condemned by Jesus’ words alongside them. We have not been completely honest in our speech. One word of dishonesty in the presence of the Truth Himself should be judged and punished. What then shall we do? As with all the Sermon on the Mount, we are compelled to look to Christ alone for our righteousness. On the cross, He stood condemned before God as if he had uttered all the blatant and vile lies in the world, yet there was no deceit found in His mouth (1 Peter 2:22). He took the punishment for all of our sinful lies and offers us His righteous record of a perfectly honest life.
My encouragement to you is this: trust Christ. Then examine your life and determine where you are the most tempted to be dishonest. Then ask God to help you be honest in that area, and pursue truthfulness for the sake of righteousness! Maybe it is in your marriage. Maybe you don’t share things with your spouse, including your feelings, anxieties, frustrations, etc. Or maybe you do say things that are untrue to cover up your faults, sins, and failures.
Maybe it is in your workplace. Do you work hard all the time, or just when someone is looking? Are you honest in your relationships? Are you dependable? Are you a man or woman of your word? Are you honest with your children, your friends, your extended family? Are you honest with your finances?
In conclusion, let me say this. One of the areas where many Christians (including myself) struggle to tell the truth is our spiritual lives. Too often we put on a mask of peace, ease, and “everything is fine,” when under the surface, we are experiencing difficulty in our walks with God or we are struggling through sin or suffering. Brothers and sisters, have we forgotten that “blessed are the poor in Spirit, for theirs is the kingdom of heaven?” (Matt 5:3). It is ok to not have it all together and recognize your need for Jesus. In fact, you are blessed if you do so.
What would it look like if we were honest with our struggles? We would “confess our sins to one another, and pray for one another, that we may be healed” (James 5:16). We could pursue honesty in our own spiritual lives and refrain from being constantly concerned with the mask we are putting on for everyone else. We could help others pursue a genuine relationship with God as well- a relationship marked by acknowledging our weakness and sin and relying completely upon his mercy and grace.
O God, help us pursue simple truth in our speech and so be witnesses to the inexhaustible beauty and glory of The Truth!
 New American Standard Bible (La Habra, CA: The Lockman Foundation, 2020), Mt 5:33–37.
 Charles Quarles, Sermon on the Mount: Restoring Christ’s Message to the Modern Church, (B&H Publishing: Nashville, TN, 2011), 139.
 Ibid., 143.