According to search-discovered classical Islamic scholarship, Zina (الزنا) is the term for unlawful sexual intercourse, encompassing both fornication (pre-marital sex) and adultery (extra-marital sex), and is unequivocally classified as a major sin (kabirah). The Quran directly addresses Zina, most notably in Surah Al-Isra (17:32), which commands believers not to even "approach" the act, a principle Ibn Kathir explains as a prohibition against all preliminary and tempting actions. Classical jurist Al-Qurtubi, in his exegesis of Surah An-Nur (24:2), elaborates on the prescribed legal punishment of one hundred lashes for unmarried perpetrators, defining it as a 'hadd'—a fixed right of Allah intended as a societal deterrent. This punishment, however, is subject to extraordinarily strict evidentiary requirements, such as the testimony of four credible male eyewitnesses to the act of penetration, a condition that makes its application exceedingly rare. The synthesis of Quranic verses (17:32, 24:2, 25:68) and scholarly analysis establishes Zina as a grave offense against God, the social fabric, and personal dignity, yet a sin for which the door of sincere repentance (Tawbah) remains wide open.