The Book of the Commencement of the Prayer
11/75. Chapter:
Reciting two surahs in one rak'ah
Sunan an-Nasai
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 صلى الله عليه وسلم يَقْرُنُ بَيْنَهُنَّ . فَذَكَرَ عِشْرِينَ سُورَةً مِنَ الْمُفَصَّلِ سُورَتَيْنِ سُورَتَيْنِ فِي رَكْعَةٍ .
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."
Reference : Sunan an-Nasa'i 1005In-book reference : Book 11, Hadith 130English translation : Vol. 2, Book 11, Hadith 1006