Sahih al-Bukhari, Hadith 6273 ⓘ
Narrated Abu Bakra: Allah's Messenger 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. "
حَدَّثَنَا عَلِيُّ بْنُ عَبْدِ اللَّهِ، حَدَّثَنَا بِشْرُ بْنُ الْمُفَضَّلِ، حَدَّثَنَا الْجُرَيْرِيُّ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ أَبِي بَكْرَةَ، عَنْ أَبِيهِ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " أَلاَ أُخْبِرُكُمْ بِأَكْبَرِ الْكَبَائِرِ ". قَالُوا بَلَى يَا رَسُولَ اللَّهِ. قَالَ " الإِشْرَاكُ بِاللَّهِ، وَعُقُوقُ الْوَالِدَيْنِ ".
also referenced under: Book 79, Hadith 47 (In-Book) & Volume 8, Book 74, Hadith 290 (USC-MSA)