Musnad Ahmad 915:1

Abdullah narrated to us, saying: Abu Bakr ibn Abi Shaybah and Muhammad ibn Abdullah ibn Numayr narrated to me—and this is the wording of Ibn Numayr’s hadith—he said: Abu Usamah narrated to us, from Abd al-Hamid ibn Ja’far, from al-Ala’ ibn Abd al-Rahman ibn Ya’qub, from his father, from Abu Hurayrah, from Ubayy ibn Ka’b, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Allah did not reveal in the Torah, nor in the Gospel, the likes of the Mother of the Quran (Umm al-Quran). It is the seven oft-repeated verses, and it is divided between Me and My servant, and for My servant is what he asks."