It was narrated from Abdullah bin Umar, from Hafsah, that:The Messenger of Allah (ﷺ) used to pray two rak'ahs when dawn had broken.
أَخْبَرَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ يَزِيدَ، قَالَ حَدَّثَنَا أَبِي قَالَ، حَدَّثَنَا جُوَيْرِيَةُ بْنُ أَسْمَاءَ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، عَنْ حَفْصَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ يُصَلِّي رَكْعَتَيْنِ إِذَا طَلَعَ الْفَجْرُ .
Nesai
The Book of Qiyam Al-Lail (The Night Prayer) and Voluntary Prayers During the Day • Hadith 1775