That is because He is the knower of invisible as well as visible; the Exalted the Merciful.
The Lord of the Universe is the Knower of Three Times, knowing everything happening in the Universe and having recorded it in His Book, as explained in verse 7: 52. Everything will perish except Him, as mentioned in verse 28: 88. He is the Knower and Observer of everything, unaffected by slumber or sleep, as mentioned in verse 2: 255. He is always with us, wherever we are, as mentioned in verse 57: 4. The Spirit (life + soul) of all creatures is from the Lord’s Spirit. When the Spirit departs from the body, it is called death. In sleep, only the soul departs while life remains in the body, as explained in verses 6: 60 and 39: 42. Allah is exalted in power, meaning that Satan from Jinn or mankind, as explained in verse 6: 112, cannot escape from His punishment nor can they defeat the Lord in any way. The Lord is Merciful only to the believers, whereas He will take revenge upon the wrongdoing Mujirims, as explained in verse 32: 22. It is mentioned in verse 33: 43 that Allah has revealed the Light—Adhikr—to deliver mankind from the different paths of Satan—darkness—into the path of Allah—the Light—and He is Merciful to the believers. The hypocrites and their blind followers, upon whom the curse and wrath of the Lord are inflicted, are in darkness, living by giving preference to bodily and worldly life without considering the soul and the Hereafter. At the time of their death, they will testify against their souls that indeed they were disbelievers, as explained in verse 7: 37. See explanation 2: 3; 31: 16.