Sunan Abi Dawud

Hadith #1256

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:]