Swearing (vv. 33–37; Lev. 19:12; Deut. 23:23). This is not the sin of “cursing,” but the sin of using oaths to affirm that what is said is true. The Pharisees used all kinds of tricks to sidestep the truth, and oaths were among them. They would avoid using the holy name of God, but they would come close by using the city of Jerusalem, heaven, earth, or some part of the body.
Jesus taught that our conversation should be so honest, and our character so true, that we would not need “crutches” to get people to believe us. Words depend on character, and oaths cannot compensate for a poor character. “In the multitude of words there wanteth not sin; but he that refraineth his lips is wise” (Prov. 10:19). The more words a man uses to convince us, the more suspicious we should be.
