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)." (3:52).
أَنَّ كَثِيرًا مِمَّا كَانَ يَقْرَأُ رَسُولُ اللَّهِ ﷺ فِي رَكْعَتَىِ الْفَجْرِ بِ { آمَنَّا بِاللَّهِ وَمَا أُنْزِلَ إِلَيْنَا } هَذِهِ الآيَةَ قَالَ هَذِهِ فِي الرَّكْعَةِ الأُولَى وَفِي الرَّكْعَةِ الآخِرَةِ بِ { آمَنَّا بِاللَّهِ وَاشْهَدْ بِأَنَّا مُسْلِمُونَ }