It was narrated from ‘Ubaid bin ‘Umair that his father — who was one of the Companions of the Prophet صلی اللہ علیہ وآلہ وسلم — told him: “A man said: ‘Messenger of Allah صلی اللہ علیہ وآلہ وسلم, 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. (Da‘if)