﴿ فَكَيْفَ تَتَّقُونَ إِن كَفَرْتُمْ يَوْمًۭا يَجْعَلُ ٱلْوِلْدَٰنَ شِيبًا ﴾

“How, then, if you refuse to acknowledge the truth, will you protect yourselves on that Day which shall turn the hair of children grey,”

So if you disbelieve in this world how will you guard against a day yawman is the direct object of tattaqūna ‘you guard against’ that is against the chastisement thereof by what defence will you defend yourselves against the chastisement of a day that will make the children grey-haired shīb is the plural of ashyab by the severity of its terrors this being the Day of Resurrection the shīn of shīb should actually have a damma but it is given a kasra because of its phonetic affinity with the yā’ — a distressing day is described as being ‘a day that makes the forelocks of children turn grey’ which is usually understood figuratively; but it may be that in the case of this verse it is meant literally —