It is narrated from Sayyiduna Ma'qil bin Yasar (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "I was given the Opening of the Book (al-Fatihah) from beneath the Throne, and the Mufassal surahs as an additional gift (nafilah)." The chain of this hadith is sahih (authentic), but the two Shaykhs (Bukhari and Muslim) did not record it.