The Messenger of Allah ﷺ used to recite in the two rakahs of Fajr. In the first, he would recite "Say, we believe in Allah and in what has been revealed to us" [Baqarah 2:136], and in the second, "We believe in Allah, and bear witness that we are Muslims" [Al-Imran 3:52].In another narration, in the second rakah he recited "Come to a word common between us and you" [Al-Imran 3:64].
كان رسول الله ﷺ يقرأ في ركعتي الفجر في الأولى منهما: {قولوا ءامنا بالله وما أنزل إلينا} [البقرة: ١٣٦] وفي الآخرة منهما: {ءامنا بالله وأشهد بأنا مسلمون} [آل عمران: ٥٢]. وفي رواية في الثانية: {تعالوا إلى كلمة سواء بيننا وبينكم} [آل عمران: ٦٤].
Muslim narrated it in "The Travelers' Prayer" (727) through Marwan bin Muawiya Fazari, and the second narration through Abu Khalid Ahmar, both of them from Uthman bin Hakeem Ansari, who said, "Saeed bin Yasar informed me that Ibn Abbas informed him," and he related the hadith.