It is reported on the authority of Abu Hurairah (RA) 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 Apostle 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'an; keep in mind, this (Surah Ikhlas) is equivalent to one-third of the Qur'an.
Hadith Referenceصحيح مسلم / کتاب فضائل القرآن وما يتعلق به / 812
Abu Hurairah (RA) reported: The Messenger of Allah (ﷺ) came out to us and said: I am going to recite before you one-third of the Qur'an. He (the Holy Prophet) then recited:" Say: He is Allah, One--Allah, the Eternal," to the end of the Surah.
Hadith Referenceصحيح مسلم / کتاب فضائل القرآن وما يتعلق به / 812
´It was narrated that Abu Hurairah said that the Messenger of Allah(ﷺ) said:` "Qul Huwa Allahu ahad [Say: He is Allah, (the) One] is equivalent to one third of the Quran."
Maulana Ataullah Sajid
Benefits and Issues:
➊ The reward of Surah Al-Ikhlas is equal to one third of the Qur'an.
➋ The reason for its greatness is that it contains the exposition of Tawhid (the Oneness of Allah).
➌ Allah Ta'ala loves Tawhid and has extreme aversion to shirk (associating partners with Him).
Source: Commentary on Sunan Ibn Mājah by Mawlānā ‘Atā’ullāh Sājid, Page: 3787