there was no other reason for abraham to seek forgiveness from god for his father except the promise that he had made with him. when abraham knew that his father was an enemy of god he disowned his father. abraham was very tenderhearted and forbearing.
وما كان استغفار إبراهيم لأبيه إلا عن موعدة وعدها إياه فلما تبين له أنه عدو لله تبرأ منه إن إبراهيم لأواه حليم