Leviticus 18:15

Or with your daughter-in-law, for she is your son's wife, and you may not take her.

Leviticus 20:12

And if a man has sex relations with his son's wife, the two of them are to be put to death: it is unnatural; their blood will be on them.

Genesis 38:26

Then Judah said openly that they were his, and said, She is more upright than I am, for I did not give her to Shelah my son. And he had no more connection with her.

Ezekiel 22:11

And in you one man has done what was disgusting with his neighbour's wife; and another has made his daughter-in-law unclean; and another has done wrong to his sister, his father's daughter.

Genesis 38:18-19

And he said, What would you have? And she said, Your ring and its cord and the stick in your hand. So he gave them to her and went in to her, and she became with child by him.

Treasury of Scripture Knowledge

Summary

Thou shalt not uncover the nakedness of thy daughter in law: she is thy son's wife; thou shalt not uncover her nakedness.

Bible References

General references

Leviticus 20:12
And if a man has sex relations with his son's wife, the two of them are to be put to death: it is unnatural; their blood will be on them.
Genesis 38:18
And he said, What would you have? And she said, Your ring and its cord and the stick in your hand. So he gave them to her and went in to her, and she became with child by him.
Ezekiel 22:11
And in you one man has done what was disgusting with his neighbour's wife; and another has made his daughter-in-law unclean; and another has done wrong to his sister, his father's daughter.

Basic English, produced by Mr C. K. Ogden of the Orthological Institute - public domain