Mukhtasar Bukhari

It is narrated from Sayyiduna Ibn Mas'ud (may Allah be pleased with him) that a man came to him and said: "I recited a Mufassal surah in one rak'ah at night," and he said, "I recited it as quickly as poetry is recited." Indeed, I know those similar surahs which the Prophet (peace and blessings of Allah be upon him) used to recite together, then he mentioned twenty Mufassal surahs (that from these) the Messenger of Allah (peace and blessings of Allah be upon him) used to recite two surahs in each rak'ah.