Narrated Abu Huraira:
Allah's Messenger (ﷺ) said, "The Um (substance) of the Qur'an is the seven oft-repeated verses (Al- Mathaini) and is the Great Qur'an (i.e. Surat-al-Fatiha).
USC-MSA web (English) reference: Vol. 6, Book 60, Hadith 227
Arabic reference: Book 65, Hadith 4704