Yahya related to me from Malik from Abd ar-Rahman ibn Abdullahibn Sasaca from his father that Abu Said al-Khudri heard a manreciting Surat al-Ikhlas (Sura 112), repeating it over and over again.In the morning he went to the Messenger of Allah, may Allah bless himand grant him peace, and mentioned it to him, as if he thought littleof it. The Messenger of Allah, may Allah bless him and grant himpeace, said, "Bythe One in whose hand my self is, it is equal to onethird of the Qur'an."
USC-MSA web (English) reference: Book 15, Hadith 17
Arabic reference: Book 15, Hadith 489