Special Virtues of the Qur’an’s Chapters and Verses

Ibn ʿAbbās reported that the Prophet ﷺ said: “Qul huwa Allāhu aḥad (Sūrat al-Ikhlāṣ) is equivalent to one-third of the Qur’ān, and Qul yā ayyuhal kāfirūn (Sūrat al-Kāfirūn) is equivalent to one-fourth of the Qur’ān.”

Reference:
Al-Silsilah al-Ṣaḥīḥah 586.