Muwatta Imam Malik Book of The Qur'an, Hadith 19

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 .