"Say: We believed in Allah and what was revealed to us..." verse 136 from Surah Baqara, and in the second of the two: "I believe in Allah and I bear testimony that we are Muslims" (iii. 52). (Using translation from Muslim 727a)
أَخْبَرَهُ أَنَّ رَسُولَ اللهِ ﷺ كَانَ يَقْرَأُ فِي رَكْعَتَيِ الْفَجْرِ فِي الْأُولَى مِنْهُمَا الْآيَةَ الَّتِي فِي الْبَقَرَةِ {قُولُوا آمَنَّا بِاللهِ وَمَا أُنْزِلَ إِلَيْنَا وَمَا أُنْزِلَ} [البقرة 136] الْآيَةَ كُلَّهَا وَفِي الْآخِرَةِ {آمَنَّا بِاللهِ وَاشْهَدْ بِأَنَّا مُسْلِمُونَ} [آل عمران 52]