(45) باب فَضْلِ قِرَاءَةِ { قُلْ هُوَ اللَّهُ أَحَدٌ}
It is reported on the authority of Abu Huraira that the Messenger of Allah (ﷺ) said:
Get together. for I am going to recite one-third of the Qur'an before you. And those who could get together gathered there. Then the Messenger of Allah (ﷺ) came out and recited:" Say: He, Allah, is One." He then entered (his house). Some of us said to the others: Perhaps there has been some news from the heaven on account of which he has gone Inside (the house). The Apostle of Allah (ﷺ) again came out and said: I told you that I was going to recite one-third of the Qur'in; keep in mind, this (Surah Ikhlas) is equivalent to one-third of the Qur'an.
Reference: Sahih Muslim 812 a
In-book reference: Book 6, Hadith 316
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 1771