Sunan Abi Dawud 1259
سنن أبي داود#1259SahihNarrated 'Abd Allah b. 'Abbas:The Messenger of Allah (ﷺ) used to recite in both rak'ahs of the dawn prayer: "Say: We believe in Allah and in the revelation given to us" (3:84) . This is in the first rak'ah and in the second rak'ah (he recited): "We believe in Allah and bear witness that we submit ourself (to Him)." (3:)
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Shuaib Al ArnautSahih
Zubair Ali ZaiSahih Muslim (727)
In-book reference: 5:10