The Messenger of Allah ﷺ said, "Umm al-Quran is the seven oft-repeated verses and the Magnificent Quran."
قال رسول الله ﷺ: أم القرآن هي السبع المثاني، والقرآن العظيم.
Bukhari narrated it in the tafsir (4704) from Adam, he said, Ibn Abu Dhib narrated to us, Saeed Maqburi narrated to us, from Abu Hurairah who said, and he mentioned it.This is what Umar, Ali, Ibn Masud, Ibn Abbas, and Abu Hurairah said among the companions, and it is what a group of the followers and those after them said. Ibn Umar, Mujahid, Saeed bin Jubayr, Dahhak, and others said it refers to the seven long surahs, meaning Baqarah, Al Imran, Nisa, Maidah, Anaam, Araf, and Yunus. This is also what Ibn Abbas said, and Ibn Masud in one narration.