A man came to Ibn Masʿud and said, "I recited the Mufassal (Suras) at night in one rakʿa." Ibn Masʿud said, "This recitation is (too quick) like the recitation of poetry. I know the identical Suras which the Prophet ﷺ used to recite in pairs." Ibn Masʿud then mentioned 20 Mufassal Suras including two Suras from the family of (i.e. those verses which begin with) Ha, Meem [??] (which the Prophet ﷺ used to recite) in each rakʿa.  

هَذًّا كَهَذِّ الشِّعْرِ لَقَدْ عَرَفْتُ النَّظَائِرَ الَّتِي كَانَ النَّبِيُّ ﷺ يَقْرِنُ بَيْنَهُنَّ فَذَكَرَ عِشْرِينَ سُورَةً مِنَ الْمُفَصَّلِ سُورَتَيْنِ فِي كُلِّ رَكْعَةٍ