Tafsir of Ya seen 36:68

"And he whom We grant long life, We reverse him in creation..."

[We reverse him in creation]: We turn him around within it, creating him in the opposite manner to how We created him before.

This is because We created him in a state of physical weakness, devoid of intellect and knowledge. Then, We caused him to increase, transitioning from one state to another, ascending from one degree to the next, until he reached his prime and attained the fullness of his strength, intellect, and knowledge of what is for him and what is against him.

Once he reaches his limit, We reverse him in creation. We cause him to diminish until he returns to a state similar to that of a child—in the weakness of his body, the scarcity of his intellect, and his lack of knowledge. This is just as an arrow is reversed, with its top turned to its bottom.

The Almighty said: "And among you is he who is returned to the most decrepit [old] age so that he knows nothing after [having had] knowledge" (Al-Hajj: 5), and "Then We returned him to the lowest of the low" (At-Tin: 5).

This is proof that He who transitions them from youth to old age, from strength to weakness, from sound judgment to senility and lack of discernment, and from knowledge to ignorance—after having transitioned them in the opposite manner—is capable of blinding their eyes, transforming them in their places, and doing with them whatever He wills and desires.

• Variants: It is read as wa-nunakkiṣuhu (with a kasrah on the kāf) and wa-nunkisuhu (from tankīs and inkās).
• [Do they not understand?]: Read with both the yā’ (third person) and the tā’ (second person).

"And We did not teach him poetry, nor is it befitting for him. It is but a reminder and a clear Qur’an, to warn whoever is alive and to justify the word against the disbelievers."