Narrated Abu Musa:

The Prophet asked for some water and performed the ablution, and then raised his hands (towards the sky) and said, "O Allah! Forgive 'Ubaid Abi 'Amir." I saw the whiteness of his armpits (while he was raising his hands) and he added, "O Allah! Upgrade him over many of Your human creatures on the Day of Resurrection "

حَدَّثَنَا مُحَمَّدُ بْنُ الْعَلاَءِ، حَدَّثَنَا أَبُو أُسَامَةَ، عَنْ بُرَيْدِ بْنِ عَبْدِ اللَّهِ، عَنْ أَبِي بُرْدَةَ، عَنْ أَبِي مُوسَى، قَالَ دَعَا النَّبِيُّ ﷺ بِمَاءٍ فَتَوَضَّأَ، ثُمَّ رَفَعَ يَدَيْهِ فَقَالَ " اللَّهُمَّ اغْفِرْ لِعُبَيْدٍ أَبِي عَامِرٍ ". وَرَأَيْتُ بَيَاضَ إِبْطَيْهِ فَقَالَ " اللَّهُمَّ اجْعَلْهُ يَوْمَ الْقِيَامَةِ فَوْقَ كَثِيرٍ مِنْ خَلْقِكَ مِنَ النَّاسِ ".