Jami` at-Tirmidhi 602

Abu Wa'il said:"A man asked Abdullah bin Mas'ud about this phrase: 'Ghairi asin' or is it Yasin? So he said: 'You can recite all of the Quran besides this [phrase]?' He said: 'Yes.' He said: 'Indeed a people recite it, disbursing it like Ad-Daqqa are dispersed, without it passing their throats. Indeed I am aware of the surahs that are comparable which the Messenger of Allah would recite together.'" He said: "So we told Alqamah to ask him (what they were). He said: "Twenty surahs from the Mufassal from which the Prophet would combine, reciting every two Surah in a Rak'ah