Musannaf Ibn Abi Shayba 22:184

Abu Usama narrated to us, from Ubaydullah, from Nafi’, from Ibn Umar, that he disliked saying "al-Mufassal," and he would say, "The entire Quran is Mufassal (divided into sections), but say 'Qisar al-Quran' (the short chapters of the Quran)."