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.


وَحَدَّثَنِي عَنْ مَالِكٍ، عَنِ ابْنِ شِهَابٍ، عَنْ حُمَيْدِ بْنِ عَبْدِ الرَّحْمَنِ بْنِ عَوْفٍ، أَنَّهُ أَخْبَرَهُ أَنَّ ‏{‏قُلْ هُوَ اللَّهُ أَحَدٌ‏}‏ تَعْدِلُ ثُلُثَ الْقُرْآنِ وَأَنَّ ‏{‏تَبَارَكَ الَّذِي بِيَدِهِ الْمُلْكُ‏}‏ تُجَادِلُ عَنْ صَاحِبِهَا ‏.‏
USC-MSA web (English) reference : Book 15, Hadith 19
Arabic reference : Book 15, Hadith 491