נָאַף

נָאַף is the verb of the seventh commandment. When Exodus 20:14 says 'you shall not commit adultery,' the word is לֹא תִּנְאָף — do not נָאַף. The word is precise: it names the breach of an existing marriage covenant through sexual union with someone other than one's spouse. Where זָנָה (H2181) covers the broader range of sexual immorality including harlotry and prostitution, נָאַף lands specifically on the person who is married and who breaks that bond. The BDB is terse: commit adultery; figuratively, apostatize. Both meanings matter for the preacher.

At the literal level, the law is clear. Leviticus 20:10 prescribes the consequence: if a man commits adultery with his neighbor's wife, both the adulterer and the adulteress shall be put to death. The law treats the act as a capital breach — not because God is harsh but because the marriage covenant is that serious. It is a covenant made before God and it carries the weight of covenant. Its breach is therefore a breach not only against the spouse but against the God who established the institution.

Proverbs 6:32 is where the word receives its wisdom literature framing: he who commits adultery (נֹאֵף אִשָּׁה) lacks sense; he who does it destroys himself. Proverbs is not primarily making a legal point here. It is making an observation about the nature of wisdom and folly. The person who breaks the marriage covenant is not merely sinning — they are acting against their own flourishing, against the ordered life that wisdom builds.

But the word's greatest theological concentration is in Jeremiah, where נָאַף is used to describe the Judah of his generation — not primarily in terms of literal sexual immorality but in terms of apostasy and spiritual betrayal. Jeremiah 9:2 describes a company of adulterers (מְנָאֲפִים). Jeremiah 23:10 says the land is full of adulterers. Jeremiah 23:14 charges the prophets of Jerusalem with adultery and walking in falsehood. And Jeremiah 29:23 names two false prophets by name and charges them with the same. In Jeremiah, נָאַף names the condition of a whole generation that has broken faith with God — religiously, morally, and covenantally — and the word chosen for that condition is the verb of the seventh commandment.

The seventh commandment is the briefest in the Decalogue and among the most contested in interpretation. Four Hebrew words: לֹא תִּנְאָף — you shall not commit adultery. No explanation of what constitutes the act. No list of exceptions. No procedural guidance. Just the prohibition, standing at the center of Israel's covenant life as a word about what the covenant itself requires: fidelity to the bond God has established.

Proverbs gives the commandment its wisdom framing. He who commits adultery lacks sense. The observation is not moralistic — it is a claim about reality. The person who breaks the marriage covenant is not merely violating a rule; they are acting against the grain of the world as God made it. Covenant fidelity is not an arbitrary restriction. It is the shape of flourishing. And its violation destroys the one who commits it, even when they believe they are gaining something. The verse is one of the clearest examples of the OT's wisdom tradition treating moral law not as external constraint but as the description of what is actually good for human beings.

Jeremiah is where the verb becomes the dominant word for a generation's spiritual condition. The prophet is not primarily concerned with his contemporaries' sexual behavior. He is concerned with their wholesale abandonment of the covenant. They have burned incense to Baal. They have built high places to Baal to burn their children in the fire. They have prophesied falsely. And Jeremiah reaches for the seventh commandment verb to name all of it: this people is full of adulterers. The word is chosen precisely because it is the right word. What Judah has done to God is what an adulterer does to their spouse — the same fundamental betrayal, the same breaking of the most intimate bond, the same turning to another while still legally, covenantally bound.

Malachi closes the OT canon with נָאַף still on the list of what the coming messenger will confront. The silence that follows in the canon before John the Baptist is preceded by this: a God who will be a swift witness against adulterers. The word that began at Sinai is still the word for what breaks the covenant, still the measure of the fidelity the covenant requires, still the charge against the generation that has forgotten what it means to belong to this God.