Yahya related to me from Malik from Abd ar-Rahman ibn Abdullah ibn Sasaca from his father that Abu Said al-Khudri heard a man reciting Surat al-Ikhlas (Sura 112), repeating it over and over again. In the morning he went to the Messenger of Allah ﷺ and mentioned it to him, as if he thought little of it. The Messenger of Allah ﷺ said, "Bythe One in whose hand my self is, it is equal to one third of the Qur'an."  

أَنَّهُ سَمِعَ رَجُلاً يَقْرَأُ قُلْ هُوَ اللَّهُ أَحَدٌ يُرَدِّدُهَا فَلَمَّا أَصْبَحَ غَدَا إِلَى رَسُولِ اللَّهِ ﷺ فَذَكَرَ ذَلِكَ لَهُ وَكَأَنَّ الرَّجُلَ يَتَقَالُّهَا فَقَالَ رَسُولُ اللَّهِ ﷺ وَالَّذِي نَفْسِي بِيَدِهِ إِنَّهَا لَتَعْدِلُ ثُلُثَ الْقُرْآنِ  

Yahya related to me from Malik from Ubaydullah ibn Abd ar-Rahman that Ubayd ibn Hunayn, the mawla of the family of Zayd ibn al Khattab, said that he had heard Abu Hurayra say, "I was going along with the Messenger of Allah ﷺ when he heard a man reciting Surat al-Ikhlas (Sura 112). The Messenger of Allah ﷺ said, 'It is obligatory,' and I asked him, 'What is, Messenger of Allah?' and he said, 'The Garden.' I wanted to tell the man the good news but I was afraid that I would miss the midday meal with the Messenger of Allah ﷺ and I preferred to eat with the Messenger of Allah ﷺ. When I went to the man afterwards I found that he had gone."  

يَقُولُ أَقْبَلْتُ مَعَ رَسُولِ اللَّهِ ﷺ فَسَمِعَ رَجُلاً يَقْرَأُ قُلْ هُوَ اللَّهُ أَحَدٌ فَقَالَ رَسُولُ اللَّهِ ﷺ وَجَبَتْ فَسَأَلْتُهُ مَاذَا يَا رَسُولَ اللَّهِ فَقَالَ الْجَنَّةُ فَقَالَ أَبُو هُرَيْرَةَ فَأَرَدْتُ أَنْ أَذْهَبَ إِلَيْهِ فَأُبَشِّرَهُ ثُمَّ فَرِقْتُ أَنْ يَفُوتَنِي الْغَدَاءُ مَعَ رَسُولِ اللَّهِ ﷺ فَآثَرْتُ الْغَدَاءَ مَعَ رَسُولِ اللَّهِ ﷺ ثُمَّ ذَهَبْتُ إِلَى الرَّجُلِ فَوَجَدْتُهُ قَدْ ذَهَبَ  

Yahya related to me from Malik from Ibn Shihab that Humayd ibn Abd ar-Rahman ibn Awf had told him that Surat al-Ikhlas (Sura 112) was equal to a third of the Qur'an, and that Surat al-Mulk (Sura 67) pleaded for its owner.  

أَنَّهُ أَخْبَرَهُ أَنَّ قُلْ هُوَ اللَّهُ أَحَدٌ تَعْدِلُ ثُلُثَ الْقُرْآنِ وَأَنَّ تَبَارَكَ الَّذِي بِيَدِهِ الْمُلْكُ تُجَادِلُ عَنْ صَاحِبِهَا