﴿ يُوفُونَ بِٱلنَّذْرِ وَيَخَافُونَ يَوْمًۭا كَانَ شَرُّهُۥ مُسْتَطِيرًۭا ﴾

“[The truly virtuous are] they [who] fulfil their vows, and stand in awe of a Day the woe of which is bound to spread far and wide,”

Allah then described their traits when they were in the life of the world, saying: (Because they perform the vow) because they fulfil their pledges and oath by Allah; it is also said this means: they perform the obligations (and fear a day) and fear the torment of a day (whereof the evil) the torment (is wide spreading,