Leviticus 18:19

“Also thou shall not approach unto a woman, etc.] Not even a man to his own wife, and much less to another woman: to uncover her nakedness, as long as she is put apart for her uncleanness; in her monthly courses; and the time of her separation from her husband on that account was seven days, (<031519>Leviticus 15:19); if a man lay with a woman when in such circumstances, they were both to be cut off from their people, (<032018>Leviticus 20:18); and such an action is reckoned among sins, and uncleanness of the worst sort, (<262210>Ezekiel 22:10).”

“As long as she is set apart - No not to thy own wife. This was not only a ceremonial pollution, but an immorality also, whence it is put amongst gross sins, Eze 18:6. And therefore it is now unlawful under the gospel. Leviticus 18:21”

“Lev 15:19, Lev 15:24, Lev 20:18; Eze 18:6, Eze 22:10 Leviticus 18:20”

“Prohibition of other kinds of unchastity and of unnatural crimes. - Lev 18:19 prohibits intercourse with a woman during her uncleanness. טמאה נדּת signifies the uncleanness of a woman's hemorrhage, whether menstruation or after childbirth, which is called in Lev 12:7; Lev 20:18, the fountain of bleeding. The guilty persons were both of them to be cut off from their nation according to Lev 20:18, i.e., to be punished with death. Lev 18:20 "To a neighbour's wife thou shalt not give שׁכבתּך thy pouring as seed" (i.e., make her pregnant), "to defile thyself with her," viz., by the emissio seminis ( Lev 15:16-17), a defilement which was to be punished as adultery by the stoning to death of both…”