According to search-discovered classical Islamic scholarship, the Quranic principle 'extends to ex-husband's heir' is derived from Surah Al-Baqarah, verse 233, specifically the phrase 'Wa 'ala al-warithi mithlu dhalik' ('And upon the heir is a duty like that'). Classical commentators, including Ibn Kathir and Al-Qurtubi, unanimously interpret this to mean that the financial obligation of a father to provide maintenance (nafaqah) for his suckling child and its nursing mother does not cease upon his death. Instead, this responsibility is transferred to the father's heir(s). Al-Tabari's analysis clarifies that this establishes a fundamental aspect of Islamic social security, ensuring a child's welfare by linking the rights of inheritance to the duties of kinship. While jurists have discussed which specific heir (e.g., the child himself if wealthy, or the father's agnates) bears this duty, the core principle of continuity of care is a matter of scholarly consensus, highlighting Islam's emphasis on protecting the rights of children.