I heard a man asking forgiveness for his parents, both of whom were polytheists, so I said, "Do you ask forgiveness for them when they are polytheists?"He replied, "Did Ibrahim not ask forgiveness for his father?"I went to the Prophet ﷺ and mentioned this to him, and then the verse was revealed, "And Ibrahim's asking forgiveness for his father was only because of a promise he had made to him" [Tawba 9:114].
سمعت رجلا يستغفر لأبويه وهما مشركان، فقلت: أتستغفر لهما وهما مشركان؟ فقال: أو لم يستغفر إبراهيم لأبيه، فأتيت النبي ﷺ فذكرت ذلك له فنزلت: {وما كان استغفار إبراهيم لأبيه إلا عن موعدة وعدها إياه} [التوبة: ١١٤].
Tirmidhi (3101) and Nasai (2036) both narrated it from the hadith of Sufyan, from Abu Ishaq, from Abu Khalil, from Ali bin Abu Talib, who related it. Tirmidhi said, "A hasan hadith." Imam Ahmad (1085) and Hakim (2/335) also reported it through this same route, and Hakim said, "sahih in isnad." Abu Khalil is Abdullah bin Khalil, or Ibn Abu Khalil, the Hadrami, the Kufan. Ibn Saad said, "He had few hadiths." Ibn Hibban deemed him reliable, and a group of narrators reported from him, so his hadith is considered hasan when supported by corroborating evidence. But when he narrates alone, his hadith needs to be examined.