The word(s) "slumber" appears 2 time(s) in 2 verse(s) in Quran in Abdullah Yusuf Ali translation.

(1) Allah! There is no god but He,-the Living, the Self-subsisting, Eternal. No slumber can seize Him nor sleep. His are all things in the heavens and on earth. Who is there can intercede in His presence except as He permitteth? He knoweth what (appeareth to His creatures as) before or after or behind them. Nor shall they compass aught of His knowledge except as He willeth. His Throne doth extend over the heavens and the earth, and He feeleth no fatigue in guarding and preserving them for He is the Most High, the Supreme (in glory).

(2) After (the excitement) of the distress, He sent down calm on a band of you overcome with slumber, while another band was stirred to anxiety by their own feelings, Moved by wrong suspicions of Allah-suspicions due to ignorance. They said: "What affair is this of ours?" Say thou: "Indeed, this affair is wholly Allah's." They hide in their minds what they dare not reveal to thee. They say (to themselves): "If we had had anything to do with this affair, We should not have been in the slaughter 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 (all this was) that Allah might test what is in your breasts and purge what is in your hearts. For Allah knoweth well the secrets of your hearts.