The Prophet ﷺ said, "Al-Kaʿba'ir (the biggest sins) are: To join others (as partners) in worship with Allah, to be undutiful to one's parents," or said, "to take a false oath." (The sub-narrator, Shuʿba is not sure) Muʿadh said: Shuʿba said, "Al-Kaʿba'ir (the biggest sins) are: (1) Joining others as partners in worship with Allah, (2) to take a false oath (3) and to be undutiful to one's parents," or said, "to murder (someone unlawfully).  

عَنِ النَّبِيِّ ﷺ قَالَ الْكَبَائِرُ الإِشْرَاكُ بِاللَّهِ وَعُقُوقُ الْوَالِدَيْنِ أَوْ قَالَ الْيَمِينُ الْغَمُوسُ شَكَّ شُعْبَةُ وَقَالَ مُعَاذٌ حَدَّثَنَا شُعْبَةُ قَالَ الْكَبَائِرُ الإِشْرَاكُ بِاللَّهِ وَالْيَمِينُ الْغَمُوسُ وَعُقُوقُ الْوَالِدَيْنِ أَوْ قَالَ وَقَتْلُ النَّفْسِ