Narrated Ibn 'Abbas:
that the Messenger of Allah (ﷺ) said: "Idha Zulzilat is equal to half of the Qur'an, Qul Huwa Allahu Ahad is equal to a third of the Qur'an, and Yul Ya Ayyuhal-Kafirun is equal to a fourth of the Qur'an." (FR)
English reference (FR): Vol. 5, Book 42, Hadith 2894 (FR)
Arabic reference (FR): Book 45, Hadith 3139 (FR)