(4) Prayer
كتاب الصلاة
(13a) Chapter: What is Recited During the Prayer - Section 1
(12) باب القراءة في الصلاة - الفصل الأول
Mishkat al-Masabih 835 
Jabir b. Samura said that the. Prophet 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.
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
 صَحِيح  (الألباني)حكم :
Reference : Mishkat al-Masabih 835
In-book reference : Book 4, Hadith 261