As-Salaam alaikum,
Chapter 109 of the Holy Qur'an, Surat Kafiruun, reads as follows:--

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."

It has been narrated by an-Nisaa'i, Tirmidhi, al-Hakim and at-Tabarani and others on the authority of Anas Ibn Malik, may Allah be pleased with him, who said the Messenger of Allah, Sallallahu alaihi Wasallam, said:--

"Qul ya ayuhal kafiruun [reading chapter 109 of the Qur'an] equals
a fourth of the Qur'an."

In another narration of Sa'ad: "Whoever recites 'Qul-ya ayuhal -Kafiruun, it is as if he recited a fourth of the Qur'an."


And it has been related by Ahmad, Abu Dawud on the authority of Nufayl Ibn Mu'awiyya who said that the Prophet, Sallallahu alaihi Wasallam, said:--

"Whenever one of you retires to his bed at night he should recite: 'Qul ya ayuhal-kafiruun
and then goes to sleep after reciting it will be free of polytheism [shirk]."


And it has been related by ad-Daylami on the authority of Abdullah Ibn Jaraad who said that the Messenger of Allah, Sallallahu alaihi Wasallam, said:--

"The hypocrite cannot pray the forenoon prayer (duhaa),
nor can he recite Qul ya ayuhal-kafiruun."