[Machine] Narrated by the Prophet ﷺ, he said, "Say, He is Allah, the One." [Al-Ikhlas 1]. One-third of the Quran. I do not know of any longer chain of transmission in an authentic hadith than this. Abu Bakr bin Ali informed me, he said, Ubaidullah and Yusuf bin Marwan narrated to us, they said, Fudail bin 'Iyad narrated to us, from Mansur, from Hilal, from 'Amr bin Maymun, from Rabi' bin Khuthaim, from Abdul Rahman bin Abi Layla, from a woman, from Abu Ayyub, he said: The Messenger of Allah ﷺ said something similar to this.  

عَنِ النَّبِيِّ ﷺ قَالَ {قُلْ هُوَ اللهُ أَحَدٌ} [الإخلاص 1] ثُلُثُ الْقُرْآنِ لَا أَعْرِفُ فِي الْحَدِيثِ الصَّحِيحِ إِسْنَادًا أَطْوَلَ مِنْ هَذَا 10450 أَخْبَرَنِي أَبُو بَكْرِ بْنِ عَلِيٍّ قَالَ حَدَّثَنَا عُبَيْدُ اللهِ وَيُوسُفُ بْنُ مَرْوَانَ قَالَا حَدَّثَنَا فُضَيْلُ بْنُ عِيَاضٍ عَنْ مَنْصُورٍ عَنْ هِلَالٍ عَنْ عَمْرِو بْنِ مَيْمُونٍ عَنْ رَبِيعِ بْنِ خُثَيْمٍ عَنْ عَبْدِ الرَّحْمَنِ بْنِ أَبِي لَيْلَى عَنِ امْرَأَةٍ عَنْ أَبِي أَيُّوبَ قَالَ قَالَ رَسُولُ اللهِ ﷺ نَحْوَهُ