Reference
ID 3514
Collector Muslim ibn al-Hajjaj
Book Sahih Muslim
Chapter The Book of Prayer (Travellers)
Reference (English Book) Book 4, Hadith 1771
Reference (Arabic Book) Book 7, Hadith 1923
Hadith Type Atar
Matn (English)

It is reported on the authority of Abu Huraira that the Messenger of Allah (may peace be upon him) 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 Apostle of Allah (may peace be upon him) 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 (may peace be upon him) 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.

Matn (Arabic)

وَحَدَّثَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، أَخْبَرَنَا مُحَمَّدُ بْنُ بَكْرٍ، حَدَّثَنَا سَعِيدُ بْنُ أَبِي عَرُوبَةَ، ح وَحَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا عَفَّانُ، حَدَّثَنَا أَبَانٌ الْعَطَّارُ، جَمِيعًا عَنْ قَتَادَةَ، بِهَذَا الإِسْنَادِ ‏.‏ وَفِي حَدِيثِهِمَا مِنْ قَوْلِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏ "‏ إِنَّ اللَّهَ جَزَّأَ الْقُرْآنَ ثَلاَثَةَ أَجْزَاءٍ فَجَعَلَ قُلْ هُوَ اللَّهُ أَحَدٌ جُزْءًا مِنْ أَجْزَاءِ الْقُرْآنِ ‏"‏ ‏.‏