Deuteronomy 5:18 is the seventh of the Ten Commandments, and it forbids adultery: sexual unfaithfulness to a marriage partner. God speaks this as a plain boundary meant to protect a covenant between a husband and a wife, and through that covenant, the wider health of the community. Moses delivers it to the people of Israel as the LORD’s own words, given again as they stand on the edge of the promised land.
“You shall not commit adultery.
Deuteronomy 5:18 (WEB)
What Deuteronomy 5:18 Means
The command is short, and its force comes from its simplicity. “You shall not” marks it as a prohibition rather than a suggestion. “Commit adultery” names a specific act: a married person giving themselves sexually to someone outside the marriage. The verse does not describe every feeling, thought, or temptation a person might have. It draws a line around a particular betrayal and says that God regards that betrayal as serious.
What the verse does not do is explain every detail of marriage, divorce, or sexuality. Those matters are developed elsewhere in Scripture. Here, God is establishing the core commitment. Faithfulness within marriage is part of how God’s people reflect his own faithfulness, and this command guards that faithfulness from being broken.
The Context of Deuteronomy 5:18
Deuteronomy presents itself as a series of addresses Moses gave to Israel before they entered Canaan. The book restates the law given at Sinai, and the Ten Commandments appear here in chapter 5 as a summary of the covenant. Israel is a people who have been rescued from slavery in Egypt, and the commandments are framed as the response of a redeemed people to the God who saved them.
The verses just before and after this one help show the pattern. Verse 15 reminds the people of their deliverance from Egypt, and verse 16 turns to honoring parents so that life may go well in the land God gives. The adultery command sits between the prohibition on murder and the prohibition on stealing, grouped with the other commands that protect life, property, and trust among neighbors. Read in that setting, adultery is not presented as a private matter alone. It damages the household, the trust that holds a community together, and the covenant relationship between God and his people.
Key Phrases in Deuteronomy 5:18
Proverbs 5:18
Let your spring be blessed. Rejoice in the wife of your youth.
(WEB)
This verse speaks of the joy of a husband and wife delighting in one another within marriage. Read beside Deuteronomy 5:18, it shows that the prohibition is not a rejection of love or pleasure but a protection of them within the covenant God designed.
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 command deeper, addressing the desire that leads toward adultery as well as the act. Read alongside Deuteronomy 5:18, it shows that God’s concern reaches into the heart as well as the body.
A Short Prayer From Deuteronomy 5:18
Lord, you are faithful when we are not. Thank you for setting boundaries that protect the people we love and the covenants we have made. Where my heart has wandered, or where I have been tempted to wander, search me and show me the path back to you. Give me wisdom to guard my marriage and my relationships with honesty and courage. Strengthen me to walk in faithfulness, and let my life reflect your steady love. Amen.
