Leviticus 20:19-23

You shall also not uncover the nakedness of your mother’s sister or of your father’s sister, for such a one has uncovered his blood relative; they will bear their guilt.

If there is a man who sleeps with his uncle’s wife, he has uncovered his uncle’s nakedness; they will bear their sin. They will die childless.

If there is a man who takes his brother’s wife, it is detestable; he has uncovered his brother’s nakedness. They will be childless.

‘You are therefore to keep all My statutes and all My ordinances, and do them, so that the land to which I am bringing you to live will not vomit you out.

Furthermore, you shall not follow the customs of the nation which I am going to drive out before you, because they did all these things; therefore I have felt disgust for them.