Messenger of Allah ﷺ said, "Shall I inform you of the biggest of the great sins?" They said, "Yes, O Allah's Apostle!" He said, "To join partners in worship with Allah, and to be undutiful to one's parents. "
قَالَ رَسُولُ اللَّهِ ﷺ أَلاَ أُخْبِرُكُمْ بِأَكْبَرِ الْكَبَائِرِ قَالُوا بَلَى يَا رَسُولَ اللَّهِ قَالَ الإِشْرَاكُ بِاللَّهِ وَعُقُوقُ الْوَالِدَيْنِ