“The Messenger of Allah ﷺ used to perform two Rak’ah before Fajr, and he used to say: ‘The best two Surah to recite in the two Rak’ah of Fajr are: “Say: Allah is One” [Al-Ikhlas (112)] and “Say: O you disbelievers.” [Al-Kafirun (109)]
كَانَ رَسُولُ اللَّهِ ﷺ يُصَلِّي رَكْعَتَيْنِ قَبْلَ الْفَجْرِ وَكَانَ يَقُولُ نِعْمَ السُّورَتَانِ هُمَا يُقْرَأُ بِهِمَا فِي رَكْعَتَىِ الْفَجْرِ {قُلْ هُوَ اللَّهُ أَحَدٌ} وَ {قُلْ يَا أَيُّهَا الْكَافِرُونَ}