Sunan Ibn Majah, Book 5, Hadith 1204 (In-Book) ⓘ
It was narrated that ‘Aishah said: “The Messenger of Allah 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)]
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا يَزِيدُ بْنُ هَارُونَ، حَدَّثَنَا الْجُرَيْرِيُّ، عَنْ عَبْدِ اللَّهِ بْنِ شَقِيقٍ، عَنْ عَائِشَةَ، قَالَتْ كَانَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ يُصَلِّي رَكْعَتَيْنِ قَبْلَ الْفَجْرِ وَكَانَ يَقُولُ " نِعْمَ السُّورَتَانِ هُمَا يُقْرَأُ بِهِمَا فِي رَكْعَتَىِ الْفَجْرِ {قُلْ هُوَ اللَّهُ أَحَدٌ} وَ {قُلْ يَا أَيُّهَا الْكَافِرُونَ} .
also referenced under: Hadith 1150 (Reference) & Volume 2, Book 5, Hadith 1150 (DarusSalam)