(5) Establishing the Prayer and the Sunnah Regarding Them
كتاب إقامة الصلاة والسنة فيها
(101) Chapter: What was narrated concerning two Rak’ah before Fajr
(101) باب مَا جَاءَ فِي الرَّكْعَتَيْنِ قَبْلَ الْفَجْرِ
Sunan Ibn Majah 1144 
It was narrated that Ibn ‘Umar said:
“The Messenger of Allah (ﷺ) used to pray two Rak’ah before the morning (prayer), as if the Adhan were in his ears. (i.e., he would pray them briefly).
حَدَّثَنَا أَحْمَدُ بْنُ عَبْدَةَ، أَنْبَأَنَا حَمَّادُ بْنُ زَيْدٍ، عَنْ أَنَسِ بْنِ سِيرِينَ، عَنِ ابْنِ عُمَرَ، قَالَ كَانَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ يُصَلِّي الرَّكْعَتَيْنِ قَبْلَ الْغَدَاةِ كَأَنَّ الأَذَانَ بِأُذُنَيْهِ ‏.‏
Grade :  Sahih (Darussalam)
Reference : Sunan Ibn Majah 1144
In-book reference : Book 5, Hadith 342
English translation : Vol. 1, Book 5, Hadith 1144