ויקרא, פרק י״ח, פסוק י״ט

After detailing the strict prohibitions against incest within the family unit, the biblical laws of sexual morality shift to restrictions that are entirely independent of blood relations [ביאור יש"ר, רד"צ הופמן]. This law applies universally to any woman, whether married or unmarried, and can compound other existing prohibitions [הכתב והקבלה]. The restriction is treated with the utmost severity, categorized alongside the most fundamental sexual offenses [אבן עזרא], and carries a distinct punishment for every individual violation in the event of multiple sins [תורה תמימה].

The physical state of menstruation inherently involves blood flowing from the body [ביאור יש"ר]. Commentators explore profound physiological and conceptual reasons for the separation required during this time. Fundamentally, marital intimacy is designed for the creation of life. Menstrual blood, however, is viewed as a substance unfit for creating life. Should a child be conceived or nourished in such a state, it is thought to be at risk of severe illness or even death [רמב"ן, הטור הארוך]. Furthermore, a state of purity is represented by a complete and sealed body. The release of bodily fluids symbolizes a breach of these physical boundaries, representing a descent from order to anarchy and from life to death. By enforcing this separation, sexuality is elevated from a base, animalistic urge to a moral, pure, and holy connection [רש"ר הירש, The Torah]. Additionally, the active state of impurity is considered physically and mentally detrimental to the partner, requiring the couple to wait until the source is fully closed [רמב"ן, הטור הארוך].

This separation is not limited solely to the days of active bleeding. The restriction remains in full force as long as the state of impurity exists, extending through the subsequent clean days until the woman completely purifies herself through immersion in water [רלב"ג, רד"צ הופמן, העמק דבר]. This standard also encompasses the accepted practice where women took upon themselves the strictness of waiting additional days beyond the base requirement [פרדס יוסף].

The primary approach among commentators is that the restriction goes far beyond the sexual act itself. It strictly forbids any form of physical closeness, including hugging, kissing, or affectionate touch, serving as a protective boundary to distance a person from sin. Yet, there is a fundamental difference between this separation and other forbidden relationships. Despite the strict ban on physical contact, a husband and his menstruating wife are completely permitted to remain alone together in privacy. Because they will be permitted to each other once again after her purification, the physical urge does not overpower them in the same way. They are considered naturally protected by their mutual restraint, guarded as if by a gentle hedge of lilies [בכור שור, פני דוד, העמק דבר]. The directive to avoid closeness is simply a mandate for the husband to pause his physical affection and patiently wait until she is pure [דעת זקנים, חזקוני].

An additional practical law arises from this prohibition in a scenario where a couple begins permitted relations, but the woman discovers she has become impure during the act. In such a situation, the husband is forbidden from withdrawing immediately. Because the physical motion of separating is itself considered an act of forbidden intimacy, he must wait until his physical arousal subsides before withdrawing [רלב"ג, צפנת פענח].