Ayat al-Kursi
ٱللَّهُ لَآ إِلَـٰهَ إِلَّا هُوَ ٱلْحَىُّ ٱلْقَيُّومُ ۚ لَا تَأْخُذُهُۥ سِنَةٌ وَلَا نَوْمٌ ۚ لَّهُۥ مَا فِى ٱلسَّمَـٰوَٰتِ وَمَا فِى ٱلْأَرْضِ ۗ مَن ذَا ٱلَّذِى يَشْفَعُ عِندَهُۥٓ إِلَّا بِإِذْنِهِۦ ۚ يَعْلَمُ مَا بَيْنَ أَيْدِيهِمْ وَمَا خَلْفَهُمْ ۖ وَلَا يُحِيطُونَ بِشَىْءٍ مِّنْ عِلْمِهِۦٓ إِلَّا بِمَا شَآءَ ۚ وَسِعَ كُرْسِيُّهُ ٱلسَّمَـٰوَٰتِ وَٱلْأَرْضَ ۖ وَلَا يَـُٔودُهُۥ حِفْظُهُمَا ۚ وَهُوَ ٱلْعَلِىُّ ٱلْعَظِيمُ
Transliteration
Allahu la ilaha illa huwa alhayyu alqayyoomu la takhuthuhu sinatun wala nawmun lahu ma fee alssamawati wama fee alardi man tha allathee yashfaAAu AAindahu illa biithnihi yaAAlamu ma bayna aydeehim wama khalfahum wala yuheetoona bishayin min AAilmihi illa bima shaa wasiAAa kursiyyuhu alssamawati waalarda wala yaooduhu hifthuhuma wahuwa alAAaliyyu alAAatheemu
Translation
Allāh - there is no deity except Him, the Ever-Living, the Self-Sustaining. Neither drowsiness overtakes Him nor sleep. To Him belongs whatever is in the heavens and whatever is on the earth. Who is it that can intercede with Him except by His permission? He knows what is [presently] before them and what will be after them, and they encompass not a thing of His knowledge except for what He wills. His Kursī extends over the heavens and the earth, and their preservation tires Him not. And He is the Most High, the Most Great.
How
Recite before sleeping.
Source: Qur'an 2:255. Full details