Exodus 20:14

Not commit adultery. This prohibition covers not only adultery but fornication and impurity of any and every kind in act, word, and thought (Matt. 5:27, 28). This, our third duty toward our “neighbour,” is to respect and honor the bond upon which the family is built, that of the marriage relationship, which to the Christian is as precious as life itself (see Heb. 13:4). Marriage makes the husband and wife “one flesh” (Gen. 2:24). To be untrue to this sacred union or to lead another to do so is to despise that which is sacred and to commit a crime as well. Throughout human history it has not generally been considered a grievous offense for the husband to become an adulterer. If, however, the wife did so, she has been dealt with most severely. Society speaks of the “fallen woman,” but little is said of the “fallen man.” The commandment applies with equal force to both husband and wife (Heb. 13:4; Rev. 21:8).