Mukhtasar Bukhari

Narrated from Sayyiduna Abu Sa'id Khudri (may Allah be pleased with him) that the Noble Prophet (peace and blessings of Allah be upon him) said to his companions (by way of rhetorical question): "Is it difficult for any one of you to recite one third of the Qur'an in a single night?" This seemed difficult to them and they said, "O Messenger of Allah! Who among us has the strength to do that?" So he (peace and blessings of Allah be upon him) said: "Surah Al-Ikhlas, in which the attributes 'Allah is One, the Self-Sufficient' are mentioned, is equal to one third of the Qur'an."