Definition and Context:
Adultery, in biblical terms, refers to a married person engaging in sexual relations with someone other than their spouse. Specifically, when a man commits adultery with another man's wife, it is considered a grave sin and a violation of the marital covenant. This act is condemned throughout the Scriptures and is seen as an offense not only against the spouse but also against God.

Biblical References:

1. The Ten Commandments:
The prohibition against adultery is explicitly stated in the Ten Commandments. Exodus 20:14 declares, "You shall not commit adultery." This commandment underscores the sanctity of marriage and the importance of fidelity.

2. Levitical Law:
The Mosaic Law provides specific instructions regarding adultery. Leviticus 20:10 states, "If a man commits adultery with another man's wife—if he commits adultery with his neighbor's wife—both the adulterer and the adulteress must surely be put to death." This severe penalty highlights the seriousness with which adultery was regarded in ancient Israelite society.

3. Wisdom Literature:
The Book of Proverbs offers warnings against the allure and consequences of adultery. Proverbs 6:32-33 warns, "He who commits adultery lacks judgment; whoever does so destroys himself. Wounds and dishonor will befall him, and his reproach will never be wiped away." This passage emphasizes the self-destructive nature of adultery and the lasting shame it brings.

4. Prophetic Writings:
The prophets often used the metaphor of adultery to describe Israel's unfaithfulness to God. For instance, Jeremiah 3:8 uses the imagery of adultery to illustrate Israel's idolatry: "Because faithless Israel had committed adultery, I gave her a certificate of divorce and sent her away." This metaphor underscores the spiritual implications of adultery as a breach of covenant.

5. New Testament Teachings:
Jesus addresses the issue of adultery in the Sermon on the Mount, expanding the understanding of the sin beyond physical acts. Matthew 5:27-28 records Jesus' words: "You have heard that it was said, 'Do not commit adultery.' But I tell you that anyone who looks at a woman to lust after her has already committed adultery with her in his heart." This teaching emphasizes the importance of purity in thought as well as in action.

6. Pauline Epistles:
The Apostle Paul reiterates the prohibition against adultery in his letters. In 1 Corinthians 6:9-10 , Paul lists adulterers among those who will not inherit the kingdom of God: "Do you not know that the wicked will not inherit the kingdom of God? Do not be deceived: Neither the sexually immoral, nor idolaters, nor adulterers, nor men who submit to or perform homosexual acts... will inherit the kingdom of God." This passage underscores the moral expectations for believers.

Cultural and Theological Implications:
Adultery, particularly involving a man and another man's wife, was not only a personal sin but also a social and communal issue in biblical times. It disrupted family structures, violated social norms, and was seen as an affront to divine law. The biblical narrative consistently portrays adultery as a serious breach of trust and fidelity, with significant spiritual and relational consequences.