Narrated Abu Hurairah:
that the Messenger of Allah (ﷺ) said: "Qul Huwa Allahu Ahad is equal to a third of the Qur'an." (TR)
English reference (TR): Vol. 5, Book 42, Hadith 2899 (TR)
Arabic reference (TR): Book 45, Hadith 3145 (TR)