Adultery is voluntary sexual intercourse by either a married man or a married woman with someone other than his or her spouse. In ancient Israel, both the man and the woman would be considered guilty. It was prohibited by both versions of the Ten Commandments (Exod. 20.14; Deut. 5.18) as well as by the Holiness Code of Leviticus (18.20). According to Leviticus 20.10, which prohibits adultery with the wife of one's neighbor, the penalty for this crime was death. The mode of execution was probably the same as that specified in Deuteronomy 22.23–24, which deals with the case of a young woman, a virgin, who was engaged to be married but met and had sexual intercourse with another man in the city. Both were guilty of adultery and were to be taken to the gate and stoned to death. This punishment is also assumed in the New Testament story of Jesus and the young woman accused of adultery, where Jesus says, “Let anyone among you who is without sin be the first to throw a stone at her” (John 8.7).
Adultery was probably considered sufficient grounds for divorce in ancient Israel. This is implied in Deuteronomy 24.1, an introduction to the law concerned with remarriage, where one interpretation of the phrase “something objectionable” has been that it refers to adultery on the part of the woman and that only this behavior justified a divorce. If a man suspected his wife of adultery but did not have any evidence, he could require her to submit to trial by ordeal, which would both determine her guilt or innocence and incorporate a physical punishment in the case of her guilt (Num. 5.11–31). In the Gospels, adultery is the only acceptable reason for divorce, although some scholars think that the phrase “except on the ground of unchastity” (Matt. 5.32) is an addition to earlier tradition (cf. Mark 10.2–12; Luke 16.18; 1 Cor. 7.10–13; Rom. 7.3).