Surah An-Nahl — Ayah 70 (16:70)
وَٱللَّهُ خَلَقَكُمۡ ثُمَّ يَتَوَفَّىٰكُمۡۚ وَمِنكُم مَّن يُرَدُّ إِلَىٰٓ أَرۡذَلِ ٱلۡعُمُرِ لِكَيۡ لَا يَعۡلَمَ بَعۡدَ عِلۡمٖ شَيۡـًٔاۚ إِنَّ ٱللَّهَ عَلِيمٞ قَدِيرٞ ٧٠
English translation (Saheeh International)
And Allāh created you; then He will take you in death. And among you is he who is reversed to the most decrepit [old] age so that he will not know, after [having had] knowledge, a thing. Indeed, Allāh is Knowing and Competent.
Brief commentary
Allah created you without a precedent; then He will cause you to die when your term of life ends. The lifespan of some of you will be extended to the worst stage of life, which is the severe old-age, when a person will no longer know anything of what he used to know. Allah is knowing, and no action of His servants is hidden from Him. He is powerful and nothing can overpower Him.