«كان إذا أخذ مضجعه قرأ {قُلْ يَا أَيُّهَا الْكَافِرُونَ} حتى يختمها»
It was the practice of the Prophet (peace and blessings be upon him):
"When he (peace and blessings be upon him) lay down on his bed, he would recite the surah 'Say: O disbelievers' (Qul ya ayyuhal-kafirun) until he completed it."
Hadith Referenceصحیح الجامع الصغیر / حرف الكاف / 4648
Hadith Gradingالألبانی:حسن
Hadith Takhrij[طب] عن عبادة بن أخضر. المشكاة ٢١٦١.