Musnad Abu Ya'la al-Mawsili 160:87

Yahya ibn Ayyub narrated to us, Ismail ibn Ja'far narrated to us, he said: Al-'Ala' informed me, from his father, from Abu Hurayrah, who said: The Messenger of Allah (ﷺ) said—and Ubayy ibn Ka'b recited the Mother of the Qur'an to him—: "By the One in Whose hand is my soul, Allah has not revealed in the Torah, nor in the Gospel, nor in the Psalms, nor in the Criterion (Al-Furqan) the like of it. Indeed, it is the seven oft-repeated verses and the Great Qur'an which I have been given."