Narrated Said bid Jubair:

Those Suras which you people call the Mufassal, are the Muhkam. And Ibn 'Abbas said, "Allah's Apostle died when I was a boy of ten years, and I had learnt the Muhkam (of the Qur'an).

حَدَّثَنِي مُوسَى بْنُ إِسْمَاعِيلَ، حَدَّثَنَا أَبُو عَوَانَةَ، عَنْ أَبِي بِشْرٍ، عَنْ سَعِيدِ بْنِ جُبَيْرٍ، قَالَ إِنَّ الَّذِي تَدْعُونَهُ الْمُفَصَّلَ هُوَ الْمُحْكَمُ، قَالَ وَقَالَ ابْنُ عَبَّاسٍ تُوُفِّيَ رَسُولُ اللَّهِ ﷺ وَأَنَا ابْنُ عَشْرِ سِنِينَ وَقَدْ قَرَأْتُ الْمُحْكَمَ.