Sahih al-Bukhari, Book 66, Hadith 59 (In-Book) ⓘ
Narrated Sa`id bin Jubair: Ibn `Abbas said, "I have learnt all the Muhkam Suras during the life time of Allah's Messenger." I said to him, 'What is meant by the Muhkam?" He replied, "The Mufassal."
حَدَّثَنَا يَعْقُوبُ بْنُ إِبْرَاهِيمَ، حَدَّثَنَا هُشَيْمٌ، أَخْبَرَنَا أَبُو بِشْرٍ، عَنْ سَعِيدِ بْنِ جُبَيْرٍ، عَنِ ابْنِ عَبَّاسٍ ـ رضى الله عنهما ـ جَمَعْتُ الْمُحْكَمَ فِي عَهْدِ رَسُولِ اللَّهِ صلى الله عليه وسلم فَقُلْتُ لَهُ وَمَا الْمُحْكَمُ قَالَ الْمُفَصَّلُ.
also referenced under: Hadith 5036 (DarusSalam) & Volume 6, Book 61, Hadith 555 (USC-MSA)