Deuteronomy 5:18 is one of the Ten Commandments, a short command that forbids sexual unfaithfulness within marriage. Moses gives it to Israel as a clear boundary that protects the covenant between husband, wife, and the God who made marriage. It is spoken by the LORD to the whole assembly of Israel, gathered as Moses recounts the law before they enter the promised land.
“You shall not commit adultery.
Deuteronomy 5:18 (WEB)
What Deuteronomy 5:18 Means
The verse is brief, but each part carries weight. “You shall not” is a direct prohibition, not a suggestion or a matter of personal preference. “Commit adultery” refers to sexual relations between a married person and someone other than their spouse. In the ancient Israelite setting, the concern was the breaking of a marriage covenant and the damage that did to families, inheritance, and trust in the community.
The verse does not spell out every related situation, such as emotional betrayal or the wider dangers of desire, and it is not a list of penalties. What it does provide is a firm line that God draws around marriage. It names a particular act and forbids it, leaving the surrounding applications to the wisdom that the rest of Scripture develops.
The Context of Deuteronomy 5:18
Deuteronomy is presented as Moses’ long address to the Israelites on the plains of Moab, shortly before they cross the Jordan. The book restates the law given at Sinai for a new generation. Chapter 5 repeats the Ten Commandments, reminding the people that the LORD spoke these words to them directly and that the covenant applies to them now, not only to their ancestors.
The verses just before the command ground it in the story of deliverance. Israel is told to keep the Sabbath because they were once slaves in Egypt and the LORD brought them out. Honoring parents comes right before it, and the commands that follow forbid murder, theft, false testimony, and coveting. Read this way, adultery is one part of a set of commands that together describe a community shaped by the faithfulness of God, where people honor one another’s life, property, household, and word.
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 to the heart, showing that the prohibition covers desire as well as the outward act. Reading it alongside Deuteronomy helps you see that God cares about the inner life as well as external behavior.
Proverbs 5:18-19
18 Let your spring be blessed. Rejoice in the wife of your youth. 19 A loving doe and a graceful deer— let her breasts satisfy you at all times. Be captivated always with her love.
(WEB)
Proverbs describes marital faithfulness as a source of joy and delight. The positive picture explains why God forbids adultery: he wants marriage to be a place of lasting satisfaction and secure love.
A Short Prayer From Deuteronomy 5:18
Lord, you made marriage good and you gave us your law to protect it. Search my heart and show me where my desires or habits are drawing me away from faithfulness to my spouse. Give me the courage to be honest, to set wise limits, and to turn from anything that threatens the covenant I have made. Let my life reflect your faithfulness to me. Amen.
