A man came to Ibn Masud and said, "I recited the entire Mufassal portion of the Quran in a single rakah tonight."Ibn Masud replied, "That is reciting as hastily as one rattles off poetry. I know well the pairs of surahs that the Prophet ﷺ used to recite together." He then mentioned twenty surahs from the Mufassal, two surahs in each rakah.
جاء رجل إلى ابن مسعود فقال: قرأت المفصل الليلة في ركعة فقال: هذا كهذ الشعر، لقد عرفت النظائر التي كان النبي ﷺ يقرن بينهن. فذكر عشرين سورة من المفصل، سورتين في كل ركعة.
Bukhari narrated it in the Book of Adhan (775), and Muslim in the Book of the Prayer of Travelers and Shortening It (822), both of them through Shuba, from Amr bin Mura, who said, I heard Abu Waail say, then he related it. The wording given is Bukhari's, and Muslim's wording is similar.