Leviticus 20:18

18 “ ‘If a man has sexual relations with a woman during her monthly period, he has exposed the source of her flow, and she has also uncovered it. Both of them are to be cut off from their people.

Read Leviticus 20:18 Using Other Translations

And if a man shall lie with a woman having her sickness, and shall uncover her nakedness; he hath discovered her fountain, and she hath uncovered the fountain of her blood: and both of them shall be cut off from among their people.
If a man lies with a woman during her menstrual period and uncovers her nakedness, he has made naked her fountain, and she has uncovered the fountain of her blood. Both of them shall be cut off from among their people.
“If a man has sexual relations with a woman during her menstrual period, both of them must be cut off from the community, for together they have exposed the source of her blood flow.

What does Leviticus 20:18 mean?

John Gill's Exposition of the Bible
Leviticus 20:18

And if a man shall lie with a woman having her sickness
Her monthly courses, which make her weak and languid, which is forbidden, ( Leviticus 18:19 ) ; this is not to be understood of a man's lying with his wife ignorantly, when in such a condition, for this being the case, he was only unclean seven days, ( Leviticus 15:24 ) ; whereas this made him and her liable to cutting off, as in an after clause; but of his lying with her, knowing this to be the case with her, and of which she could not be ignorant, and therefore both liable to the same punishment; or else of any other man lying with her, or of any man lying with any woman, married or unmarried, being in such circumstances: and shall uncover her nakedness;
that is, have carnal knowledge of her: he hath discovered her fountain;
from whence her issue of blood flows: and she hath uncovered the fountain of her blood; freely and willingly, as Aben Ezra observes; for if she had been forced, he alone would have been cut off; but both these phrases put together show agreement in this matter, that they both had knowledge of her case, and both consented to commit the sin: and both of them shall be cut off from among their people;
by death, either by the hand of the civil magistrate, the case being known and proved, or else by the hand of God being known by mortality or the pestilence, as the Targum of Jonathan, or they should die childless; (See Gill on Leviticus 20:17).

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