Reported by Abu Sa`id Al-Khudri (RA): A man heard another reciting Surat Al-Ikhlas repeatedly. The next morning he came to the Messenger of Allah (peace be upon him) and informed him about it as if he considered it to be of little reward. On that the Messenger of Allah (peace be upon him) said, "By Him in Whose Hand my soul is, this Surah is equal to one-third of the Qur'an.''
[Al-Bukhari]