abraham only asked for forgiveness for his father because of a promise he had made to him. but when it became clear to him that he was an enemy of allah he declared himself quit of him. surely abraham was earnest in his supplication and tenderhearted.
وما كان استغفار إبراهيم لأبيه إلا عن موعدة وعدها إياه فلما تبين له أنه عدو لله تبرأ منه إن إبراهيم لأواه حليم