The word(s) "slumber" appears 3 time(s) in 3 verse(s) in Quran in Mohsin Khan translation.

(1) Allah! La ilaha illa Huwa (none has the right to be worshipped but He), Al-Hayyul-Qayyum (the Ever Living, the One Who sustains and protects all that exists). Neither slumber nor sleep overtakes Him. To Him belongs whatever is in the heavens and whatever is on the earth. Who is he that can intercede with Him except with His Permission? He knows what happens to them (His creatures) in this world, and what will happen to them in the Hereafter. And they will never compass anything of His Knowledge except that which He wills. His Kursi extends over the heavens and the earth, and He feels no fatigue in guarding and preserving them. And He is the Most High, the Most Great. [This Verse 2:255 is called Ayat-ul-Kursi ]

(2) Then after the distress, He sent down security for you. slumber overtook a party of you, while another party was thinking about themselves (as how to save their ownselves, ignoring the others and the Prophet صلى الله عليه وسلم) and thought wrongly of Allah - the thought of ignorance. They said, "Have we any part in the affair?" Say (O Muhammad صلى الله عليه وسلم): "Indeed the affair belongs wholly to Allah." They hide within themselves what they dare not reveal to you, saying: "If we had anything to do with the affair, none of us would have been killed here." Say: "Even if you had remained in your homes, those for whom death was decreed would certainly have gone forth to the place of their death," but that Allah might test what is in your breasts; and to purify that which was in your hearts (sins), and Allah is All-Knower of what is in (your) breasts.

(3) (Remember) when He covered you with a slumber as a security from Him, and He caused water (rain) to descend on you from the sky, to clean you thereby and to remove from you the Rijz (whispering, evil-suggestions) of Shaitan (Satan), and to strengthen your hearts, and make your feet firm thereby.