The Victory”. The title of the XLVIIIth Surah of the Qur’an, in the first verse of which the word occurs, “Verily We (God) have given thee an obvious victory, that God may pardon thee thy former and later sin.”
Professor Palmer says, “Some of the commentators take this to mean sins committed by Muhammad before his call and after it. Others refer to the word to the liaison with the Coptic handmaiden Mary, and to his marriage with Zainab, the wife of his adopted son Zaid.” None of the commentators we have consulted, including al-Baizawi, al-Jalalan, al-Kamalan, and Husain, give the last interpretation. They all say it refers to his sins before and after his call to the Apostleship.
Based on Hughes, Dictionary of Islam