ויקרא, פרק י״ח, פסוק כ׳

Violating the sanctity of marriage and interpersonal trust strikes at the very core of human morality. Adultery is not merely an offense against a husband; it is a profound destruction of personal sanctity and purity. This prohibition applies broadly to any fellow human being [ביאור שטיינזלץ], encompassing all of humanity [ביאור יש"ר], with the exception of a captive woman [אבן עזרא].

Unlike prohibitions regarding family members, which are framed around the disrespect and violation of familial closeness, adultery is addressed with direct and simple language focused on the physical act itself [רמב״ן, רד״צ הופמן]. Furthermore, while certain sexual prohibitions are divine decrees that transcend human logic, adultery is a universally recognized moral outrage. Because its inherent wickedness is obvious to the human mind, it requires no abstract terminology to convey its severity [ביאור יש"ר, רד״צ הופמן].

The law specifically highlights the aspect of conception, which prompts significant discussion since the severe penalty applies regardless of the physical outcome. The primary approach among commentators offers three conceptual layers to explain this focus. First, it addresses the motive. Even if a person acts entirely devoid of animalistic lust, driven solely by the noble desire to bring children into the world—such as seeking to build a family through a friend's wife because one's own wife is barren—the act remains an absolute and severe violation [אבן עזרא, טור, רבנו בחיי, תולדות יצחק, נחל קדומים, העמק דבר].

Second, highlighting conception underscores the destructive consequences of the sin. Adultery creates agonizing doubt regarding paternity, leading to a heartbreaking reality where a man might sacrifice his entire life and inheritance for a child he falsely believes to be his own. God profoundly despises this specific injustice [רמב״ן, בכור שור, רד״צ הופמן]. Finally, focusing on conception defines the exact boundaries of the punishment. It clarifies that the ultimate penalty of spiritual excision is reserved strictly for the physical act of intercourse, rather than inappropriate affection like hugging or kissing [רמב״ן, טור, רבנו בחיי, ביאור יש"ר], and legally excludes acts involving physical impotence [רמב״ן, תורה תמימה, רלב״ג, בכור שור].

The aftermath of this betrayal is a profound defilement. This is not a standard ritual impurity that can be washed away in a ritual bath, but an irreversible spiritual corruption that fundamentally dismantles a person's moral foundation [ביאור יש"ר, רש"ר הירש, ברכת אשר, רד״צ הופמן]. King Solomon likened adultery to walking on burning coals, as the sin literally scorches the body in this world and condemns the soul in the next [רבנו בחיי]. Legally, the lasting impact on the woman’s marriage depends entirely on her consent. If she acts willingly, she becomes permanently forbidden to her husband, but if she is a victim of circumstance or acts unintentionally, her marriage remains intact [תורה תמימה].

The destructive ripple effects of this sin extend into the next generation. Placed directly alongside the prohibition of child sacrifice to idols, the law conveys a sharp warning: children born from the impurity of adultery are rooted in spiritual darkness and are destined to deteriorate into idolatry and the desecration of God's name, as true success can never blossom from sin [תולדות יצחק]. Because these forbidden relationships carry such grave consequences and present a constant human struggle—especially during historical periods when young men and women would court and socialize—this specific reading was instituted for the peak of Yom Kippur to serve as a stark, sobering warning to the public [פרדס יוסף].