Removing the arrow from the body

Narrated Abu Musa:

Abu 'Amir was hit with an arrow in his knee, so I went to him and he asked me to remove the arrow. When I removed it, the water started dribbling from it. Then I went to the Prophet and told him about it. He said, "O Allah! Forgive 'Ubaid Abu 'Amir."

حَدَّثَنَا مُحَمَّدُ بْنُ الْعَلاَءِ، حَدَّثَنَا أَبُو أُسَامَةَ، عَنْ بُرَيْدِ بْنِ عَبْدِ اللَّهِ، عَنْ أَبِي بُرْدَةَ، عَنْ أَبِي مُوسَى ـ رضى الله عنه ـ قَالَ رُمِيَ أَبُو عَامِرٍ فِي رُكْبَتِهِ، فَانْتَهَيْتُ إِلَيْهِ قَالَ انْزِعْ هَذَا السَّهْمَ. فَنَزَعْتُهُ، فَنَزَا مِنْهُ الْمَاءُ، فَدَخَلْتُ عَلَى النَّبِيِّ ﷺ فَأَخْبَرْتُهُ، فَقَالَ " اللَّهُمَّ اغْفِرْ لِعُبَيْدٍ أَبِي عَامِرٍ ".