Leviticus 20:12
And if a man lie with his daughter in law, both of them shall surely be put to death: they have wrought confusion; their blood shall be upon them. And if a man lie with his daughter in law, both of them shall surely be put to death: they have wrought confusion; their blood shall be upon them.
The verse stands in Leviticus 18-20, part of Leviticus 5-23 dealing largely with laws relating to sacrifices and offerings, the consecration and duties of the priests, and the yearly feasts. It belongs among the laws contrasting what God gave to Israel with the pagan abominations and evil practices of the nations cast out of the Holy Land before Israel, and showing the consequences of those practices. Those nations had given themselves up to rule by Satan through the flesh after four hundred years of mercy while filling up their cup of iniquity.
The verse forbids a man to have sexual relations with his daughter-in-law, identifying it as a prohibited degree of marriage and as incest. The prohibited union with a daughter-in-law falls within the degrees of affinity. The prohibition remains in force because it rests on moral considerations.
The verse emphasizes the exceeding sinfulness of sin through a severe object lesson. Both the man and his daughter-in-law who commit this sexual act shall surely be put to death. Lying with a daughter-in-law in this way violates the seventh commandment. Their act is called confusion because it mixes family relationships in ways that disrupt clear relationships and spiritual discernment, and their blood shall be upon them, meaning they bear responsibility for its bloodguilt.