Narrated Shaqiq: `Abdullah said, "I learnt An-Naza'ir which the Prophet used to recite in pairs in each rak`a." Then `Abdullah got up and Alqama accompanied him to his house, and when Alqama came out, we asked him (about those Suras). He said, "They are twenty Suras that start from the beginning of Al- Mufassal, according to the arrangement done be Ibn Mas`ud, and end with the Suras starting with Ha Mim, e.g. Ha Mim (the Smoke). and "About what they question one another?" (78.1)

Narrated Abu Wa'il: A man came to Ibn Mas`ud and said, "I recited the Mufassal (Suras) at night in one rak`a." Ibn Mas`ud said, "This recitation is (too quick) like the recitation of poetry. I know the identical Suras which the Prophet used to recite in pairs." Ibn Mas`ud then mentioned 20 Mufassal Suras including two Suras from the family of (i.e. those verses which begin with) Ha, Meem [??] (which the Prophet used to recite) in each rak`a.