The Messenger of Allah ﷺ used to recite in the dawn prayer, in the first rakah, "We believe in Allah and in what was revealed to us and what was revealed to Ibrahim" [Baqarah 2:136] to the end of the verse, and in the second rakah, "We believe in Allah, so bear witness that we are Muslims" [Aal Imran 3:52].
حدثنا ابن نمير حدثنا عثمان بن حكيم قال أخبرني سعيد بن يسار
أن رسول الله ﷺ كان يقرأ في الفجر في أول ركعة {آمنا بالله وما أنزل إلينا وما أنزل إلى إبراهيم} إلى آخر الآية وفي الركعة الثانية {آمنا بالله واشهد بأنا مسلمون}
Its isnad is sahih. It is found in Muslim 1:201–202 and Sunan Abu Dawud 1/487. Uthman bin Hakeem bin Abbad bin Hunayf, his reliability was already established at 408, and in the two original manuscripts here it appears as "Uthman bin Abu Hakeem," which is an error. Saeed bin Yasar, Abu Hubab, with the ha vowelled with a damma and the ba unshaddaded, was a reliable Medinan successor. Ibn Abdul-Barr said, "They do not disagree about his reliability." The hadith was narrated by Muslim, Abu Dawud, and Nasai, as noted in Dhakhair Mawarith 2806. See also Muntaqa 918. It will come again at 2045 and 2386.