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  

The Prophet ﷺ said, "The biggest sins are: To join others in worship with Allah; to be undutiful to one's parents; to kill somebody unlawfully; and to take an oath Al-Ghamus. (Using translation from Bukhārī 6675)   

قَالَ رَسُولُ اللهِ ﷺ الْكَبَائِرُ الشِّرْكُ بِاللهِ وَعُقُوقُ الْوَالِدَيْنِ وَقَتْلُ النَّفْسِ وَقَوْلُ الزُّورِ  

The Prophet ﷺ was asked about the great sins He said, "They are:-- (1 ) To join others in worship with Allah, (2) To be undutiful to one's parents. (3) To kill a person (which Allah has forbidden to kill) (i.e. to commit the crime of murdering). (4) And to give a false witness." (Using translation from Bukhārī 2653)   

قَالَ رَسُولُ اللهِ ﷺ «الْكَبَائِرُ الْإِشْرَاكُ بِاللهِ وَعُقُوقُ الْوَالِدَيْنِ وَقَتْلُ النَّفْسِ وَقَوْلُ الزُّورِ»  

"أَكْبَرُ الكبائر: الإشْراكُ بالله، وَقَتْلُ النَّفْسِ وعُقُوقُ الْوَالدينِ، وشهادةُ الزُّورِ، أو قول الزُّورِ ".  

"الْكَبَائِرُ: الشِّرْكُ باللهِ، وقَتْلُ النَّفْسِ، وَعقُوقُ الْوَالِدْين، ألا أُنَبِّئُكُمْ بأَكبَر الْكَبَائِر؟ قَوْلُ الزُّورِ، أوْ شَهَادَةُ الزُّورِ" .  

"إِنَّ اكبر الْكَبائِر الإِشراكُ باللَّه وعُقُوقُ الوالدين ومنْعُ فَضْل الْمَاءِ، ومنعُ الْفَحل".