Furwah bin Nawfal narrated from his father (Sayyiduna Nawfal رضي الله عنه) that the Messenger of Allah صلى الله عليه وسلم said to him: "What has brought you (to me)?" He replied: "I have come so that you may teach me something which I can recite when I go to sleep." The Prophet صلى الله عليه وسلم said: "When you lie down on your bed, recite «﴿قُلْيَاأَيُّهَاالْكَافِرُونَ﴾» and at its end go to sleep, for this surah is a declaration of innocence from shirk (association with Allah)." (i.e., it absolves one from shirk.)
Hadith Referenceسنن دارمي / من كتاب فضائل القرآن / 3459
Hadith Takhrijاس حدیث کی سند صحیح ہے۔ دیکھئے: [أبوداؤد 5055] ، [ترمذي 3403] ، [أبويعلی 1596] ، [ابن حبان 789] ، [موارد الظمآن 2363] ، [فضائل القرآن لأبي عبيد، ص: 264] و [النسائي فى الكبريٰ 10627]
Brief Explanation
(Commentary on Hadith 3458)
From this hadith, the virtue of Surah al-Kafirun is understood, due to the fact that in it there is an explicit rejection of the worship of false deities and an affirmation of remaining steadfast upon one's own religion.