Hadith 5035
Narrated Sa`id bin 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).
Hadith 5036
Narrated Sa`id bin Jubair: Ibn `Abbas said, "I have learnt all the Muhkam Suras during the life time of Allah's Apostle." I said to him, 'What is meant by the Muhkam?" He replied, "The Mufassal."