If reciting Surah Al-Ikhlas three times is equal in reward to reciting the whole Qur’an, would a Muslim be committing a sin if they leave reciting the whole Qur’an, finding sufficiency in this Surah?
It is authentically reported that the Messenger of Allah (peace be upon him) said:
'Religion is sincerity (in acts, advice, and so on),' which he (peace be upon him) repeated three times. It was asked, 'To whom, O Messenger of Allah?' He (peace be upon him) said, 'To Allah, His Book, His Messenger, the leaders of the Muslims, and the common Muslims.'
Sincerity to the Book of Allah (Exalted be He) is achieved by reciting it, contemplating the meaning of its Ayahs, following its admonitions, and abiding by its rules through obeying its commands and avoiding its prohibitions. Undoubtedly, reciting only Surah Al-Ikhlas instead of the entire Qur’an is incompatible with being sincere to Allah’s Book. This is also against sincerity to oneself, because it deprives the person of the rewards to be gained from reading the whole Qur’an, from increasing one’s Iman (faith), and knowing what is Halal (lawful), Haram (prohibited), Wajib (obligatory), Sunnah (supererogatory), or Makruh (disliked), in addition to acquiring the good manners and morals preached in the Qur’an. Indeed, depravation of these great virtues is a sufficient deterrent to every Muslim against forsaking reading the Book of Allah. Although the Messenger of Allah (peace be upon him) knew well the virtue and reward of reciting Surah Al-Ikhlas, and stated that it is equal to one-third of the Qur’an,
and was most desirous of earning a generous reward from Allah, he (peace be upon him) never restricted himself to reciting this Surah alone and used to recite the whole Book of Allah. (Part No. 4; Page No. 30) Allah (Exalted be He) says:
Indeed, in the Messenger of Allâh (Muhammad صلى الله عليه وسلم) you have a good example to follow.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and companions.