It is Allah who creates you and takes your souls at death; and of you there are some who are sent back to a feeble age, so that they know nothing after having known (much): for Allah is All-Knowing, All-Powerful. An-Nahl 16:70 ⧉
Tafsir:
Life as it manifests itself on the earth presents many aspects—one who was non-existent comes into being in the world; then everybody dies, but not at one time. Somebody dies in childhood and another in youth and yet another in old age. Then it is a very strange occurrence that at the last stage of his life, a man loses his mental powers, his knowledge and his physical strength completely. Man is apparently free in the present world. But he has no control over any aspect of his life. All this happens to show man that perfect knowledge and power belong only to God. Man has no say in the above-mentioned type of events that occur in a man’s life: he is not capable of bringing about any change in them. This proves that whatever is happening is happening at the instance of some other being; man’s life as a whole, right from childhood up to his death, bears testimony to the fact that here all knowledge belongs to God and all power rests with God—man’s helplessness is the proof of the all-powerful existence of God.