ויקרא, פרק כ׳, פסוק י״א

The family unit is treated with the utmost reverence, and any violation of its boundaries is viewed as a profound betrayal. A son engaging in relations with his father's wife commits far more than a moral failing; it is a fundamental distortion of the natural order and a devastating blow to the family's honor. The act is described using language that implies merely lying down to satisfy physical lust, deliberately avoiding the terminology typically reserved for a proper, purposeful union meant for creating life. This choice of description highlights the sheer degradation of the act. The sinner suppresses his higher, intellectual nature, reducing himself to the level of an animal driven entirely by raw instinct [הכתב והקבלה].

The severity of this boundary applies equally regardless of the exact family dynamic. The prohibition and its consequences are identical whether the woman is the son's own mother or another wife of his father. Furthermore, this boundary is permanent, remaining fully in force even after the father has passed away [מלבי״ם, חזקוני, אדרת אליהו, רד״צ הופמן].

The horror of the act is magnified by the direct shame it brings upon the father. It is considered an exceedingly grave offense [אבן עזרא] because the ultimate disgrace falls upon the patriarch of the family [ביאור שטיינזלץ, ביאור יש״ר, מלבי״ם]. This profound disrespect is rooted in the unnatural distortion of mixing the seed of both the father and the son within the same woman [רלב״ג]. On a deeper, spiritual level, this betrayal transcends the earthly family. The offense is ultimately directed against the Heavenly Father, God Himself, which elevates the severity of the sin [שפתי כהן].

The consequence for such a severe breach is absolute, requiring the death of both individuals involved. They share the punishment equally because the woman bears full responsibility for her role in allowing or facilitating the sin [רד״צ הופמן]. The legal terminology used to finalize their guilt is highly specific. Rather than a simple statement of blame, this precise phrasing functions as a legal directive. Throughout the Torah, whenever this specific declaration of guilt appears in the context of capital punishment, it dictates that the execution must be carried out by stoning [תורה תמימה, נתינה לגר].