His father - who was one of the Companions of the Prophet [SAW] - told him: "A man said: 'O Messenger of Allah, what are the major sins?' He said: 'They are seven; the most grievous of which are associating others with Allah, killing a soul unlawfully and fleeing (from the battlefield) on the day of the march.'" It is abridged.
أَنَّهُ حَدَّثَهُ أَبُوهُ وَكَانَ مِنْ أَصْحَابِ النَّبِيِّ ﷺ أَنَّ رَجُلاً قَالَ يَا رَسُولَ اللَّهِ مَا الْكَبَائِرُ قَالَ هُنَّ سَبْعٌ أَعْظَمُهُنَّ إِشْرَاكٌ بِاللَّهِ وَقَتْلُ النَّفْسِ بِغَيْرِ حَقٍّ وَفِرَارٌ يَوْمَ الزَّحْفِ مُخْتَصَرٌ