صَحِيحُ مُسْلِمٍ
Sahih Muslim 724 e
The Book of Prayer - Travellers
It is recommended to pray two rak`ah for the sunnah of Fajr. And encouragement to pray them regularly, and to make them brief, and to persist in offering them, and clarifying what is recommended to recite therein
حَدَّثَنَا عُبَيْدُ اللَّهِ بْنُ مُعَاذٍ، حَدَّثَنَا أَبِي، حَدَّثَنَا شُعْبَةُ، عَنْ مُحَمَّدِ بْنِ عَبْدِ الرَّحْمَنِ الأَنْصَارِيِّ، سَمِعَ عَمْرَةَ بِنْتَ عَبْدِ الرَّحْمَنِ، عَنْ عَائِشَةَ، قَالَتْ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم إِذَا طَلَعَ الْفَجْرُ صَلَّى رَكْعَتَيْنِ أَقُولُ هَلْ يَقْرَأُ فِيهِمَا بِفَاتِحَةِ الْكِتَابِ .
'A'isha reported: When it was dawn, the Messenger of Allah (ﷺ) observed two rak'ahs, and I would say: Does he recite only the opening chapter of the Qur'an in it?
Sahih Muslim, 724 eSahihصحيح