Leviticus 18:15 Commentary: Daughter-in-Law Prohibition

Leviticus 18 stands within the Holiness Code (chapters 17-26), a block of laws calling Israel to reflect God’s character through sexual and social purity. Verses 6-18 form a unit headed by the general command not to approach any near kin, then list specific prohibited relationships. The repeated formula 'uncover nakedness' is a Hebrew euphemism for sexual intercourse, implying the shame of violating a family boundary.

The list protects the structure of the extended family, which in ancient Israel was the basic unit of identity, inheritance, and worship. Marriages created not just a bond between individuals but between family groups. A daughter-in-law was adopted into her husband’s clan; to have sex with her would confuse generations and destabilize the household. The same logic appears in the surrounding verses: a man’s sister (v.9), aunt (v.12-13), and brother’s wife (v.16) are all forbidden.

A significant historical question is the relationship of this prohibition to the levirate marriage law in Deuteronomy 25:5-6, which requires a brother to marry his deceased brother’s widow to preserve the family line. Leviticus 18:16 forbids a man from uncovering the nakedness of his brother’s wife, creating an apparent contradiction. Rabbinic tradition resolved this by treating the levirate command as a special exception to the general prohibition. For daughter-in-law (v.15), a similar tension arises: the marital bond creates a permanent kinship, but if the son dies childless, does the father have a duty similar to a brother? The Old Testament does not command a father to marry his daughter-in-law, and the severity of the penalty in Leviticus 20:12, death, suggests the command holds even after the son’s death. Yet the story of Judah and Tamar (Genesis 38) shows a daughter-in-law expecting to marry within the family, though she is given to a brother, not the father. This historical background shows that the precise boundaries of these laws were carefully debated within Israel and later in Jewish and Christian interpretation.

The consulted sources note no significant textual variants for Leviticus 18:15. The verse is consistent across all major manuscript traditions. The key interpretive difficulty lies in its relationship to other biblical commands, not in the wording itself.

In Jewish tradition, rabbinic literature treated this verse as a permanent prohibition. The Mishnah and Talmud discuss the degrees of incest derived from Leviticus 18, and the prohibition against a daughter-in-law was upheld even after the son’s death, with the levirate exception applying only to a brother’s wife, not to a father’s daughter-in-law. Christian interpreters from the early church onward generally read the command as absolute, using it to establish the lasting bond created by marriage. Matthew Henry and John Gill both treat it as forbidding marriage after the son’s death, reflecting a common Protestant view. In the medieval period, canon law used this and related verses to set boundaries for marriage between in-laws. The verse continues to inform ethical discussions about family boundaries and the sanctity of the marital bond.

Three-point outline

1. God protects family order by drawing clear boundaries. The repeated formula 'uncover nakedness' marks sexual intimacy as belonging within marriage alone. Each forbidden relationship safeguards the structure God designed for human flourishing.
2. Marriage creates permanent kinship. The reason clause 'she is your son’s wife' grounds the prohibition not in blood but in the bond marriage makes. This bond endures beyond death, a truth that shapes how Christians think about marriage and family.
3. God’s law carries weight and grace. The death penalty in Leviticus 20:12 shows the seriousness of the command, but the broader biblical story includes redemption for failures, Judah’s confession over Tamar points to a God who forgives even while upholding His standards.

Five-point outline

1. The text: a clear prohibition. The Hebrew construction, לֹא with an imperfect, creates a permanent, absolute ban. No loophole is offered in the verse itself.
2. The reason: 'she is your son’s wife'. Kinship by marriage is treated as real as blood kinship. This has consequences for how Christians view in-law relationships.
3. The penalty: a warning. Leviticus 20:12 calls it 'perversion' (tebel), a mixing of categories that defiles the land and the people.
4. The tension: levirate marriage. The command to marry a brother’s widow (Deuteronomy 25:5-6) seems to contradict Leviticus 18:16. Resolving this teaches us how to handle apparently conflicting laws, interpreters later saw the levirate as a divine exception to a general rule.
5. The application for today: While the specific circumstances (daughter-in-law unions) may not be common, the principle of honoring family boundaries and the permanence of marriage ties remains. Christians are called to build relationships that reflect the holiness and order of God.

Illustration hooks

• The awkwardness of holiday gatherings when family lines blur: a reminder that boundaries are gifts, not restrictions.
• A family tree diagram: one misconnected branch can confuse the whole chart. God’s law prevents that confusion.
• The legal system’s prohibition of marriage between close in-laws (e.g., a parent and child’s spouse): secular law mirrors the ancient wisdom of this verse.

Questions your congregation is asking

• Does this verse apply after a son has died? Can a widower marry his former daughter-in-law?
• How do we reconcile this with levirate marriage in the Old Testament?
• What does this ancient law have to do with my family relationships today?

This verse sits within a list of sexual prohibitions given to Israel as they prepared to enter the land. They were to be different from the nations around them, especially in how they treated family relationships. Read Leviticus 18:1-5 and 24-30 to set the context, then focus on verse 15. Consider what it reveals about God’s design for marriage and family.

Discussion questions

1. What does the phrase 'uncover the nakedness of your daughter-in-law' mean in plain English? Why do you think the Bible uses this indirect language?
2. The verse gives a reason for the prohibition: 'She is your son’s wife.' What makes that relationship close enough to forbid sexual contact? How does marriage create kinship?
3. Compare this verse with Leviticus 18:6, the general command not to approach any near kin. How does the specific rule illustrate the general principle?
4. Read Leviticus 20:12. Why is the penalty so severe, death for both parties? What does that tell us about how seriously God takes family order?
5. The practice of levirate marriage (Deuteronomy 25:5-6) commands a man to marry his brother’s widow. How does that relate to Leviticus 18:16 (brother’s wife) and to this verse about a daughter-in-law? Do you see a contradiction or an exception?
6. In Genesis 38, Judah has a sexual encounter with his daughter-in-law Tamar, thinking she is a prostitute. When he learns the truth, he says she is more righteous than he. What does this story add to our understanding of the law here?
7. How might this ancient command shape how Christians today think about boundaries with in-laws or other extended family members? What is the healthy principle behind the rule?