Allāh presents an example: a man [i.e., slave] owned by quarreling partners and another belonging exclusively to one man - are they equal in comparison? Praise be to Allāh! But most of them do not know.
(And indeed We have put forth for men, in this Qur'an every kind of parable) means, `We have explained things to mankind in it the Qur'an by setting forth examples and parables.'
لَعَلَّهُمْ يَتَذَكَّرُونَ
(in order that they may remember.) Because parables bring the meaning closer to people's minds. As Allah says:
ضَرَبَ لَكُمْ مَّثَلاً مِّنْ أَنفُسِكُمْ
(He sets forth for you a parable from yourselves) (30:28). meaning, `so that you may learn it from yourselves.' And Allah says:
Verse أَفَمَن يَتَّقِي بِوَجْهِهِ (Tell Me about the one who tries to save himself from the worst punishment with his face ...) carries a description of the terrifying scenario of Jahannam. If one faces something hurtful in his mortal life, he tries to fight it off by using his hands and feet as defensive shields to protect his face. But, refuge with Allah, the people of Jahannam will not be able to use even their hands and feet to defend themselves. The punishment that comes will fall directly on their faces. Even if he wished to ward off the punishment in defense, he would have no option but to use his very face as the shield, because he would have been thrown in Jahannam with his hands and feet tied. We seek refuge with Allah from such a fate.
Out of the authorities of Tafsir, ` Ata and Ibn Zayd said that a person condemned to Jahannam will have his hands and feet tied before being dragged in there. (Qurtubi)
Tazkirul Quran
Maulana Wahiduddin KhanOn ayahs 26–30
Man always tries to save his face from injuries, but the punishment of Doomsday will so encompass man that it will not be possible for him to save any part of his body. In fact he will stand before the ineluctable punishment, as if using his face as a shield against it. In the eyes of God, the greatest crime a man can commit is not to admit to the Truth when it reveals itself to him. Such people can never escape the scourge of God.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.