A man came to him and said, "I recited the entire Mufassal portion tonight in a single rakah."He replied, "That is rushing through it like reciting poetry. I know well the pairs that the Prophet ﷺ used to recite together," and he mentioned twenty surahs from the Mufassal, two surahs in each rakah.
جاء رجل إليه 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 Prayer of Travelers (279/722), both through the route of Shuba, from Amr bin Mura, who said, I heard Abu Waail say, A man came to Abdullah bin Masud, and he mentioned the hadith. Muslim named this man, in the narration of Abu Bakr bin Abu Shayba, from Waki, from Amash, from Abu Waail, as "Nahik bin Sinan." In it, Abdullah said, "Is this like the rapid recitation of poetry? There are people who recite the Quran, but it does not pass beyond their collarbones. But when it settles in the heart and takes root there, it benefits. The best part of the prayer is the ruku and the sujud. I know the paired surahs which the Messenger of Allahﷺ used to combine, two surahs in each rakat."In the narration of Abu Muawiya, from Amash, it states, "Twenty surahs from the Mufassal, according to the arrangement of Abdullah." Ibn Khuzayma (538) mentioned the details of this in the narration of Abu Khalid from Amash. They are twenty surahs from the arrangement of Abdullah. The first of them is Rahman, and the last of them is Dukhan. Rahman and Najm in one rakat, Dhariyat and Tur in one rakat (these are the paired surahs), Iqtarabat and Haqqah in one rakat, Waqiah and Nun in one rakat, Naziat and Sa ala Sail in one rakat, Mudaththir and Muzzammil in one rakat, Wayl lil-Mutaffifin and Abasa in one rakat, Wala Uqsimu and Hal Ata in one rakat, Mursalat and Amma Yatasaalun in one rakat, and Idha ash-Shamsu Kuwwirat and Dukhan in one rakat.Abu Dawud (1396) also narrated it likewise, from Abbad bin Musa, who said, Ismail bin Jafar narrated to us, from Israil, from Abu Ishaq, from Alqama and Aswad, who both said, A man came to Ibn Masud and said, "I recite the Mufassal in a single rakat." He said, "Is this like the rapid recitation of poetry, and prose scattered like scattered dates? Rather, the Prophetﷺ used to recite the paired surahs, two surahs in a rakat." Then he mentioned the details as before.Abu Dawud said, "This is the arrangement of Ibn Masud." The Mufassal, according to the sahih view, extends from Qaf to the end of the Quran, as the Hafiz stated.His saying, "the paired surahs" means the surahs that resemble one another in their meanings, such as admonition, or wisdom, or narratives.His saying, "hadhdh" with a fatha on the ha and a doubled dhal, means rapid, unbroken recitation, excessive in speed. It is in the accusative as a verbal noun, and it is a rhetorical question of disapproval, with the interrogative particle omitted. He said this because that manner was their custom in reciting poetry. This is as stated in Fath al-Bari.