Hadithcore
Sunan Abi Dawud, 5055
sahih· Al-Albani

Farwah b. Nawfal quoted his father as saying that the Prophet (ﷺ) said to Nawfal (his father):

Recite (the Surah) 'Say, O you disbelievers!' and then go to sleep at its end, for it is a declaration of freedom from polytheism.

حَدَّثَنَا النُّفَيْلِيُّ، حَدَّثَنَا زُهَيْرٌ، حَدَّثَنَا أَبُو إِسْحَاقَ، عَنْ فَرْوَةَ بْنِ نَوْفَلٍ، عَنْ أَبِيهِ، أَنَّ النَّبِيَّ صلى الله عليه وسلم قَالَ لِنَوْفَلٍ ‏

‏ اقْرَأْ ‏{‏ قُلْ يَا أَيُّهَا الْكَافِرُونَ ‏}‏ ثُمَّ نَمْ عَلَى خَاتِمَتِهَا فَإِنَّهَا بَرَاءَةٌ مِنَ الشِّرْكِ ‏

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References2 variants
In-Book Reference
Book 43, Hadith 283
English Reference
Book 42, Hadith 5037