Sunan an-Nasa'i 1005
It was narrated that 'Amr bin Murrah said:
"I heard Abu Wa'il say: "A man said in the presence of Abdullah: 'I recited Al-Mufassal in one rak'ah.' He said: 'That is like reciting poetry. I know the similar surahs that the Messenger of Allah ﷺ used to recite together.' And he mentioned twenty surahs from Al-Mufassal, two by two in each rak'ah."
أَخْبَرَنَا إِسْمَاعِيلُ بْنُ مَسْعُودٍ، قَالَ حَدَّثَنَا خَالِدٌ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنْ عَمْرِو بْنِ مُرَّةَ، قَالَ سَمِعْتُ أَبَا وَائِلٍ، يَقُولُ قَالَ رَجُلٌ عِنْدَ عَبْدِ اللَّهِ قَرَأْتُ الْمُفَصَّلَ فِي رَكْعَةٍ . قَالَ هَذًّا كَهَذِّ الشِّعْرِ لَقَدْ عَرَفْتُ النَّظَائِرَ الَّتِي كَانَ رَسُولُ اللَّهِ ﷺ يَقْرُنُ بَيْنَهُنَّ . فَذَكَرَ عِشْرِينَ سُورَةً مِنَ الْمُفَصَّلِ سُورَتَيْنِ سُورَتَيْنِ فِي رَكْعَةٍ .