Hafsa reported that when it was dawn, the Messenger of Allah ﷺ did not observe (any other prayers) but two short rak'ahs.  

كَانَ رَسُولُ اللَّهِ ﷺ إِذَا طَلَعَ الْفَجْرُ لاَ يُصَلِّي إِلاَّ رَكْعَتَيْنِ خَفِيفَتَيْنِ  

The Messenger of Allah ﷺ used to pray two rak'ahs when dawn had broken.  

أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ يُصَلِّي رَكْعَتَيْنِ إِذَا طَلَعَ الْفَجْرُ  

"When dawn came, the Messenger of Allah ﷺ would not pray anything but two brief rak'ahs."  

أَنَّهَا قَالَتْ كَانَ رَسُولُ اللَّهِ ﷺ إِذَا طَلَعَ الْفَجْرُ لاَ يُصَلِّي إِلاَّ رَكْعَتَيْنِ خَفِيفَتَيْنِ  

"When the dawn appears, the Messenger of Allah ﷺ would only pray two short Rak'ahs."  

أَنَّهَا قَالَتْ كَانَ رَسُولُ اللَّهِ ﷺ إِذَا طَلَعَ الْفَجْرُ لاَ يُصَلِّي إِلاَّ رَكْعَتَيْنِ خَفِيفَتَيْنِ  

[Machine] The Prophet ﷺ used to pray two quick prostrations after the break of dawn, which was a time when he would not enter upon the Prophet ﷺ.  

أَنَّ النَّبِيَّ ﷺ كَانَ «يُصَلِّي سَجْدَتَيْنِ خَفِيفَتَيْنِ بَعْدَمَا يَطْلُعُ الْفَجْرُ وَكَانَتْ سَاعَةً لَا أَدْخُلُ فِيهَا عَلَى النَّبِيِّ ﷺ»  

It was narrated from Ibn ‘Umar that when the dawn illuminated, the Prophet ﷺ would pray two Rak’ah. (Using translation from Ibn Mājah 1143)   

أَنَّ النَّبِيَّ ﷺ كَانَ إِذَا طَلَعَ الْفَجْرُ صَلَّى رَكْعَتَيْنِ