SURA 109. Kafirun, or Those who reject Faith
1. Say : O ye that reject Faith!
2. I worship not that which ye worship,
3. Nor will ye worship that which I worship.
4. And I will not worship that which ye have been wont to worship,
5. Nor will ye worship that which I worship.
6. To you be your Way, and to me mine.
Hadrat Abdullah bin Umar (may Allah be pleased with him) has related that on many an occasion he heard the Holy Prophet recite Surahs Qul Ya- ayyuhal- kafirun and Qul Huwu-Allahu ahad in the two rakahs before the Fajr obligatory Prayer and in the two rakahs after the Maghrib obligatory Prayer. Several traditions on this subject with a little variation in wording have been related by Imam Ahmad, Tirmidhi, Nasai, Ibn Majah, Ibn Hibban, Ibn Marduyah from Ibn Umar.
Hadrat Khabbab says: “The Holy Prophet (upon whom be peace) said to me: when you lie down in bed to sleep, recite Qul ya-ayyuhal kafirun, and this was the Holy Prophet’s own practice also; when he lay down to sleep, he recited this Surah.” (Bazzar, Tabarani, Ibn Marduyah).
According to Ibn Abbas, the Holy Prophet (upon whom be peace) said to the people: “Should I tell you the word which will protect you from polytheism? It is that you should recite Qul ya-ayyuhal kafirun when you go to bed.”(Abu Ya’la, Tabarani).
Hadrat Anas says that the Holy Prophet said to Hadrat Mu’adh bin Jabal; “Recite Qul ya-ayyuhal-kafirun at the time you go to bed, for this is immunity from polytheism.” (Baihaqi in Ash-Shu’ab).
Both Fardah bin Naufal and Abdur Rahman bin Naufal have stated that their father, Naufal bin Muawiyah al-Ashjai, said to the Holy Prophet (upon whom be peace): “Teach me something which I may recite at the time I go to bed.” The Holy Prophet replied: “Recite Qul ya-ayyuhal kafirun to the end and then sleep, for this is immunity from polytheism.” (Musnad Ahmad, Aba Da’ud, Tirmidhi, Nasai, Ibn Abi Shaibah, Hakim, Ibn Marduyah, Baihaqi in Ash-Shuab). A similar request was made by Hadrat Jabalah bin Harithah, brother of Hadrat Said bin Harithah, to the Holy Prophet and to him also he gave the same reply. (Musnad Ahmad, Tabarani).
Source: Sayyid Abul Ala Maududi – Tafhim al-Qur’an – The Meaning of the Qur’an