Leviticus 18:15

You must not expose your daughter-in-law's nakedness; she [is] your son's wife; you must not expose her nakedness.

Leviticus 20:12

As for a man who lies with his daughter-in-law, both of them shall be put to death; they have committed a perversion--their blood [is] on them.

Genesis 38:26

Then Judah recognized [them] and said, "She is more righteous than I, since I did not give her to my son Shelah." And he did not know her again.

Ezekiel 22:11

And a man does a detestable thing [with] the wife of his neighbor, and a man defiles his daughter-in-law in wickedness, and a man sexually violates among you his sister, the daughter of his father.

Genesis 38:18-19

And he said, "What [is] the pledge that I must give to you?" And she said, "your seal, your cord, and your staff that [is] in your hand." And he gave [them] to her and went in to her. And she conceived 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
As for a man who lies with his daughter-in-law, both of them shall be put to death; they have committed a perversion--their blood [is] on them.
Genesis 38:18
And he said, "What [is] the pledge that I must give to you?" And she said, "your seal, your cord, and your staff that [is] in your hand." And he gave [them] to her and went in to her. And she conceived by him.
Ezekiel 22:11
And a man does a detestable thing [with] the wife of his neighbor, and a man defiles his daughter-in-law in wickedness, and a man sexually violates among you his sister, the daughter of his father.