Ā'ishah رضي الله عنها narrated that the Messenger of Allah ﷺ used to say at night if he turned during sleep:
لَا إِلَهَ إِلَّا اللَّهُ الْـوَاحِدُ الْقَهَّـارُ، رَبُّ السَّـمَاوَاتِ وَالْأَرْضِ وَمَا بَيْـنَهُمَا الْعَزيـزُ الْغَـفَّارُ
Lā ilāha illa llāhu l-wāḥidu l-qahhār, rabbu s-samāwāti wa l-arḍi wa mā baynahuma l-‘azīzu l-ghaffār.
Translation
None has the right to be worshipped except Allaah, the One, the All-Subduing (Al-Qahhar); Lord of the heavens and the earth and all that is between them, the Almighty, the Oft-Forgiving.
When to recite
When turning over in bed during the night.
Source / Reference
Hisnul Muslim 108