According to search-discovered classical Islamic scholarship, altering a bequest (Tabdeel al-Wasiyyah) is a Quranically defined act that carries severe consequences if done unjustly but is a duty if done to correct a sin or error. The foundational ruling in Surah Al-Baqarah, verse 2:181, establishes the sanctity of a person's final will, stating unequivocally that 'whoever alters it after he has heard it, the sin is only upon those who alter it.' Ibn Kathir emphasizes this divine warning, noting that Allah is All-Hearing of the will and All-Knowing of the alteration. However, this prohibition is balanced by the principle of justice in the subsequent verse, 2:182. Al-Qurtubi and other jurists explain that if a testator commits an error or sin ('janfan aw ithman'), such as bequeathing more than the legal one-third or disinheriting a rightful heir, it is the responsibility of the executor to intervene and 'make peace between the parties concerned.' This corrective action is not a sin but an act of 'islah' (reconciliation) that restores the will's alignment with divine law. The synthesis of these two verses creates a robust ethical framework for executors: to faithfully execute a just will and to courageously correct an unjust one, all under the knowledge that Allah is the ultimate witness.