﴿ 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,”

They fulfil their vows pledged in obedience to God and fear a day the evil of which will be widespread.