Dua For Forgiveness of Your Siblings

رَبِّ اغْفِرْ لِي وَلِأَخِي وَأَدْخِلْنَا فِي رَحْمَتِكَ ۖ وَأَنْتَ أَرْحَمُ الرَّاحِمِينَ

O my Lord! Forgive me and my brother, and make us enter into Your Mercy, for you are the Most Merciful of those who show mercy.

Pronunciation: Rabbi ighfir lee wali akhee wa adkhilna fee rahmatika wa anta arhamur rahimeen

Reference: Surah Al-A'raf - 7:151