Dua #1.
رَبَّنَا آمَنَّا فَاغْفِرْ لَنَا وَارْحَمْنَا وَأَنتَ خَيْرُ الرَّاحِمِينَ
المؤمنون :109
Rabbana amanna faghfir lana warhamna wa anta khayrur Rahimiin
Our Lord! We have believed, so forgive us and have Mercy upon us, and surely You are the Best of the Merciful. - 23: 109
This is a dua made by a group of Muslims. They used to continuously make this dua.
In this dua the believers are addressing Allah I by saying, “O Allah I we have brought Iman, hence forgive us and have mercy on us”.