He (the Holy Prophet) shortened the prayer and he did not pray like these people then, and he informed me that the Messenger of Allah ﷺ used to recite" Qaf. By the (Glorious) Qur'an," and a passage of similar length.
عَنْ صَلاَةِ النَّبِيِّ ﷺ فَقَالَ كَانَ يُخَفِّفُ الصَّلاَةَ وَلاَ يُصَلِّي صَلاَةَ هَؤُلاَءِ قَالَ وَأَنْبَأَنِي أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ يَقْرَأُ فِي الْفَجْرِ ب { ق وَالْقُرْآنِ} وَنَحْوِهَا