Sahih Muslim Book 004, Hadith Number 1795.
Chapter : "The Qur'an has been revealed in seven modes of "reading" and its meaning.
Shaqiq reported: A person from Banu Bajila who was called Nabik b. Sinan came to Abdullah and said: I recite mufassal surahs in one rak'ah. Upon this 'Abdullah said: (You recite) like the recitation of poetry. I know the manner in which the Messenger of Allah (may peace be upon him) recited two surahs in one rak'ah.