וְ֠אִישׁ אֲשֶׁר־יִשְׁכַּ֨ב אֶת־אִשָּׁ֜ה דָּוָ֗ה וְגִלָּ֤ה אֶת־עֶרְוָתָהּ֙ אֶת־מְקֹרָ֣הּ הֶֽעֱרָ֔ה וְהִ֕יא גִּלְּתָ֖ה אֶת־מְק֣וֹר דָּמֶ֑יהָ וְנִכְרְת֥וּ שְׁנֵיהֶ֖ם מִקֶּ֥רֶב עַמָּֽם׃
And if a man shall lie with a woman having her sickness, and shall uncover her nakedness—he hath made naked her fountain, and she hath uncovered the fountain of her blood—both of them shall be cut off from among their people.
Read kabbalistic (mystical) interpretation of Leviticus 20:18: and classical mystical sources.