King James Bible
"Again, ye have heard that it hath been said by them of old time, Thou shalt not forswear thyself, but shalt perform unto the Lord thine oaths:"
Jesus continues his Sermon on the Mount pattern of citing traditional Jewish teachings. This formula signals he will reinterpret or deepen an established commandment, positioning himself as an authoritative teacher who builds upon Moses' law. This prohibition against false swearing summarizes Old Testament teachings about perjury and breaking vows (Leviticus 19:12, Numbers 30:2). The term encompasses both lying under oath and failing to fulfill sworn promises. The positive counterpart emphasizes that oaths invoke God as witness, making them sacred obligations. This reflects the ancient Jewish understanding that vows were not merely social contracts but spiritual commitments before God himself.