The Criterion for Sleep That Invalidates Ablution and Wiping Over Socks

Question:
Finally, he asks: What is the criterion for the sleep that invalidates wudu' (ablution) and from which a person must perform wudu'? And is it permissible to wipe over the known socks if they were put on while in a state of purity?

Answer:
The sleep that invalidates wudu' is deep sleep, such as when one is lying down or sitting and leaning on something, where if that thing were to fall, he would fall with it. This is what invalidates wudu' because at that time he does not trust himself, and it is a state where the exit of impurities is possible. So sleep was made to invalidate wudu' because it is in the position of the exit of impurities, if it is deep sleep. As for light drowsiness of a person who is sitting and in control of himself, this does not harm, because the Companions (may Allah be pleased with them) used to wait for the prayer with the Messenger of Allah (peace and blessings be upon him) until their heads would nod, and when they stood up to pray, they did not perform wudu' because they were sitting. This is drowsiness less than what is free from drowsiness. And as for the rest regarding wiping over socks: if they are covering and the socks cover the foot, covering the ankles, and everything below the ankles of the rest of the foot to the toes is covered, and they were worn while in a state of purity, the correct view is that he wipes over them, because the Prophet (peace and blessings be upon him) wiped over the sandals and over the socks. Yes.