Musnad Abu Ya'la al-Mawsili 110:162

Abu Bakr narrated to us, Mu'awiyah ibn Hisham narrated to us, from 'Ammar ibn Ruzayq, from 'Abdullah ibn 'Isa, from Sa'id ibn Jubayr, from Ibn 'Abbas, who said: While Jibril was sitting with the Prophet, may Allah bless him and grant him peace, he heard a creaking sound from above him. He raised his head and said: "This is a gate from the heaven that has been opened; it has never been opened before." Then an angel came to him and said: "Receive glad tidings of two lights that you have been given, which no prophet before you was given: the Opening of the Book (Al-Fatihah) and the concluding verses of Surat Al-Baqarah. You will not recite a single letter from them without being granted it."