And Allah the Exalted said in Surah Al-Muzzammil «ورتل القرآن ترتيلا‏» : "And recite the Qur'an with measured recitation." (That is, pronounce each letter properly and with calmness.) And in Surah Bani Isra'il He said «وقرآنا فرقناه لتقرأه على الناس على مكث‏» : "And We have sent down the Qur'an in stages so that you may recite it to the people at intervals." And it is disliked to recite it hastily like poetry. Ibn Abbas (may Allah be pleased with them both) said: The word «فرقناه‏» in this Surah means that We revealed it in parts.

Narrated Abu Wail: We went to `Abdullah in the morning and a man said, "Yesterday I recited all the Mufassal Suras." On that `Abdullah said, "That is very quick, and we have the (Prophet's) recitation, and I remember very well the recitation of those Suras which the Prophet used to recite, and they were eighteen Suras from the Mufassal, and two Suras from the Suras that start with Ha Mim.