Sahih Muslim Book - 44, Hadith - 6333

حَدَّثَنَا أَبُو كُرَيْبٍ ، حَدَّثَنَا يَحْيَى بْنُ آدَمَ ، حَدَّثَنَا قُطْبَةُ ، عَنِ الأَعْمَشِ ، عَنْ مُسْلِمٍ ، عَنْ مَسْرُوقٍ ، عَنْ عَبْدِ اللهِ ، قَالَ : وَالَّذِي لاَ إِلَهَ غَيْرُهُ مَا مِنْ كِتَابِ اللهِ سُورَةٌ إِلاَّ أَنَا أَعْلَمُ حَيْثُ نَزَلَتْ ، وَمَا مِنْ آيَةٍ إِلاَّ أَنَا أَعْلَمُ فِيمَا أُنْزِلَتْ ، وَلَوْ أَعْلَمُ أَحَدًا هُوَ أَعْلَمُ بِكِتَابِ اللهِ مِنِّي ، تَبْلُغُهُ الإِبِلُ ، لَرَكِبْتُ إِلَيْهِ.

It was narrated that 'Abdullah said: "By the One besides Whom there is none worthy of worship, there is no Surah in the Book of Allah but I know best where it was revealed, and there is no Verse but I know best concerning what it was revealed. If I knew that someone was more knowledgeable of the Book of Allah than myself, and I could reach him by camel, I would ride to where he is."