Surah Ya-Sin 36:68

وَمَن نُّعَمِّرْهُ نُنَكِّسْهُ فِى ٱلْخَلْقِ ۖ أَفَلَا يَعْقِلُونَ

And he to whom We grant long life We reverse in creation; so will they not understand?

Translation: Saheeh International

Tafsir

And whomever We give long life by prolonging his term of life We cause him to regress nankushu; a variant reading has 2nd verbal form nunakkishu derived from al-tankīs in creation that is in terms of his physical form so that after having enjoyed strength and youth he becomes feeble and decrepit. …

Excerpt from Tafsir al-Jalalayn, commentary on 36:68, via Quran.com. The reader has the full commentary and 9 more tafsirs.