مِشْكَاةُ الْمَصَابِيحِ
Mishkat al-Masabih 835
Prayer
What is Recited During the Prayer - Section 1
وَعَنْ جَابِرِ بْنِ سَمُرَةَ قَالَ: كَانَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَقْرَأُ فِي الْفَجْرِ ب (ق وَالْقُرْآن الْمجِيد) وَنَحْوِهَا وَكَانَتْ صَلَاتُهُ بَعْدُ تَخْفِيفًا. رَوَاهُ مُسْلِمٌ
Jabir b. Samura said that the. Prophet (ﷺ) used to recite at the dawn prayer, "Qaf. By the glorious Qur'an"* and a passage of similar length, and his prayer afterwards was shortened. *Al-Qur’an; 50. Muslim transmitted it.
Mishkat al-Masabih, 835صَحِيح (الألباني)