Tafsir of Al-Muzzammil 73:17

{فَكَيْفَ تَتَّقُونَ إِن كَفَرْتُمْ يَوْمًا}

{يَوْمًا}: It is the direct object (maf‘ūl bihi). The meaning is: How will you protect yourselves on the Day of Resurrection—which belongs to Him—if you remain in disbelief and do not believe or perform righteous deeds?

It is also permissible for it to be an adverb of time (ẓarf), meaning: How will you attain piety on the Day of Resurrection if you disbelieved in the worldly life?

It is also permissible for it to be in the accusative case governed by kafartum (if interpreted as jaḥadtum [you denied]), meaning: How will you fear and revere Allah if you deny the Day of Resurrection and the recompense? This is because the fear of Allah is the fear of His punishment.

{يَجْعَلُ الْوِلْدَانَ شِيبًا}: This is a metaphor for intensity. It is said regarding a severe day: "A day that turns the forelocks of children gray." The origin of this is that when worries and sorrows overwhelm a person, gray hair accelerates in them. Abu al-Tayyib [al-Mutanabbi] said: And worry wastes away the robust body, And turns the boy’s forelock gray, and ages him.

I have come across in some books that a man went to sleep with hair as black as a raven’s wing, and woke up with a head and beard as white as the thaghamah (a white-flowered plant). He said: "I saw the Resurrection, Paradise, and Hell in a dream, and I saw people being led in chains to the Fire. From the terror of that, I became as you see."

It is also possible that the day is being described by its length, meaning that children reach the age of old age and grayness within it.

{السَّمَاءُ مُنفَطِرٌ بِهِ}: This is also a description of the day’s intensity. It means that the sky, despite its greatness and solidity, will split asunder on that day. What, then, do you think of other creatures?

It has been recited as munfaṭir and mutafaṭir. The meaning is: "possessing the quality of splitting." Or, it is interpreted as the sky being a "roof," or interpreted as "the sky is a thing that is split."

The ba’ in {بِهِ} (by it) is like your saying: "I split the stick with the axe, so it split by it." It means the sky splits due to the intensity of that day—which belongs to Him—just as a thing splits by that which causes it to split.

It is also permissible that the meaning is: The sky is burdened by it with a weight that leads to its splitting due to its magnitude upon it and its fear of its occurrence, as in His saying: {It is heavy in the heavens and the earth} [Al-A‘rāf: 187].

{وَعْدُهُ}: This is an instance of the verbal noun being attributed to the object (maf‘ūl), and the pronoun refers to the Day. It is also permissible for it to be attributed to the Agent, who is Allah—Mighty and Majestic is He—even though He was not explicitly mentioned, because He is known.

{إِنَّ هَذِهِ تَذْكِرَةٌ فَمَن شَاءَ اتَّخَذَ إِلَى رَبِّهِ سَبِيلًا}