The Book of Qiyam Al-Lail (The Night Prayer) and Voluntary Prayers During the Day
20/60. Chapter:
The time for the two rak'ahs of Fajr, and mentioning the differences reported from Nafi'
Sunan an-Nasai
أَخْبَرَنَا يَحْيَى بْنُ مُحَمَّدٍ، قَالَ حَدَّثَنَا مُحَمَّدُ بْنُ جَهْضَمٍ، قَالَ إِسْمَاعِيلُ حَدَّثَنَا عَنْ عُمَرَ بْنِ نَافِعٍ، عَنْ أَبِيهِ، عَنِ ابْنِ عُمَرَ، قَالَ أَخْبَرَتْنِي حَفْصَةُ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ يُصَلِّي قَبْلَ الصُّبْحِ رَكْعَتَيْنِ .
It was narrated that Ibn 'Umar said: "Hafsah told me that the Messenger of Allah (ﷺ) used to pray two rak'ahs beore Subh."
Reference : Sunan an-Nasa'i 1770In-book reference : Book 20, Hadith 173English translation : Vol. 2, Book 20, Hadith 1771