Deuteronomy 5:18 is a short, direct command from God: you must not commit adultery. It forbids sexual unfaithfulness to another person’s spouse, and by extension it protects the covenant of marriage as something God takes seriously. Moses speaks this law to the people of Israel as part of the Ten Commandments, which he repeats to a new generation before they enter the promised land.
“You shall not commit adultery.
Deuteronomy 5:18 (WEB)
What Deuteronomy 5:18 Means
The verb “commit” points to a deliberate act, not an accident or a feeling. The command names a specific betrayal: sexual relations with someone who belongs to another person through marriage. In the ancient Israelite setting, that betrayal damaged a household, a family line, and the trust that held a community together, so the law guards those relationships at their most vulnerable point.
What the verse does not do is spell out every related temptation, every thought, or every boundary a person might set in their own life. It states a clear prohibition and trusts the reader to see how it applies across the wider teaching of Scripture. It also does not promise that a person who keeps this command will never face a painful marriage or that obedience guarantees a happy home. It names what God requires and why it matters.
The Context of Deuteronomy 5:18
Deuteronomy is Moses’ farewell address, spoken on the plains of Moab as Israel prepares to cross the Jordan. Traditionally Moses is credited with the book, and it is addressed to the whole nation, including a generation that had not stood at Sinai. Chapter 5 restates the Ten Commandments in a setting of remembrance, opening with God reminding Israel that he had rescued them from slavery in Egypt.
The commandment sits in a list of five consecutive prohibitions, between the command against murder and the command against theft. Its neighbors show that the law addresses the whole shape of community life: the sanctity of life, the sanctity of marriage, the sanctity of property, and the truthfulness of speech. Read in that company, the prohibition on adultery is one part of a coherent picture of a people who belong to a faithful God and are called to reflect that faithfulness toward one another.
Key Phrases in Deuteronomy 5:18
Matthew 5:27-28
27 “You have heard that it was said, ‘You shall not commit adultery;’ 28 but I tell you that everyone who gazes at a woman to lust after her has committed adultery with her already in his heart.
(WEB)
Jesus takes the commandment deeper, showing that lust in the heart is part of the same reality the law addresses. Reading this passage alongside Deuteronomy 5:18 reveals that God’s concern reaches beyond outward action to the desires that lead toward it.
Hebrews 13:4
Let marriage be held in honor among all, and let the bed be undefiled: but God will judge the sexually immoral and adulterers.
(WEB)
This verse honors marriage as something held in high regard and affirms that God judges those who break faith within it. It reinforces the honor Deuteronomy 5:18 protects and shows that the command comes from a God who cares for marriage.
A Short Prayer From Deuteronomy 5:18
Lord, you are faithful, and you have made marriage a picture of the trust you keep with your people. Search my heart where I have been careless with my affections or with the boundaries I need. Give me courage to be honest, wisdom to flee temptation, and a love for my spouse that is steady and clean. Where I have already stumbled, lead me to confession and to the grace of your forgiveness. Help me to honor the vows I have made and to keep my eyes, my words, and my steps faithful to them. Amen.
