Sunan Abi Dawud 1256
سنن أبي داود#1256Sahihحَدَّثَنَا يَحْيَى بْنُ مَعِينٍ، حَدَّثَنَا مَرْوَانُ بْنُ مُعَاوِيَةَ، حَدَّثَنَا يَزِيدُ بْنُ كَيْسَانَ، عَنْ أَبِي حَازِمٍ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ النَّبِيَّ صلى الله عليه وسلم قَرَأَ فِي رَكْعَتَىِ الْفَجْرِ { قُلْ يَا أَيُّهَا الْكَافِرُونَ } وَ { قُلْ هُوَ اللَّهُ أَحَدٌ } .
Narrated Abu Hurairah:The Prophet (ﷺ) would recite in the two (supererogatory) rak'ahs of the dawn prayer: "Say, O unbelievers" [Surat al-Kafiroon:1] and "Say: He is Allah, the one" [Surat al-Ikhlas:]
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
In-book reference: 5:7