once
يَقْرَأُ ﴿الم﴾ تَنْزِيلَ السَّجْدَة ِ، وَتَبَارَكَ الَّذي بِيَدِهِ الْمُلْكُ
Meaning
The Prophet never used to sleep until he had recited Soorat As-Sajdah (chapter 32) and Soorat Al-Mulk (chapter 67).
Source and references
Hisn al-Muslim, entry 110.The reference is copied from the edition; separate editorial verification is not complete yet.
Source edition: Fortress of the Muslim. Open source ↗