Leviticus 20:21

Overview - Leviticus 20
Of him that gives of his seed to Moloch.
Of him that favours such an one.
Of going to wizards.
Of sanctification.
Of him that curses his parents.
10 Of adultery.
11 Of incest.
13 Of sodomy.
15 Of bestiality.
18 Of uncleanness.
22 Obedience is required with holiness.
27 Wizards must be put to death.
Treasury of Scripture Knowledge

Leviticus 20:21  (King James Version)
And if a man shall take his brother's wife, it is an unclean thing: he hath uncovered his brother's nakedness; they shall be childless.

his brother's
18:16 Matthew 14:3 Matthew 14:4

an unclean thing
Hebrew a separation.