Narrated Abu Wail:Abu Musa and Abii Mas`ud went to `Ammar when `Ali had sent him to Kufa to exhort them to fight (on `Ali's side). They said to him, "Since you have become a Muslim, we have never seen you doing a deed more criticizable to us than your haste in this matter." `Ammar said, "Since you (both) became Muslims, I have never seen you doing a deed more criticizable to me than your keeping away from this matter." Then Abu Mas`ud provided `Ammar and Abu Musa with two-piece outfits to wear, and one of them went to the mosque (of Kufa).
حَدَّثَنَا بَدَلُ بْنُ الْمُحَبَّرِ، حَدَّثَنَا شُعْبَةُ، أَخْبَرَنِي عَمْرٌو، سَمِعْتُ أَبَا وَائِلٍ، يَقُولُ دَخَلَ أَبُو مُوسَى وَأَبُو مَسْعُودٍ عَلَى عَمَّارٍ حَيْثُ بَعَثَهُ عَلِيٌّ إِلَى أَهْلِ الْكُوفَةِ يَسْتَنْفِرُهُمْ فَقَالاَ مَا رَأَيْنَاكَ أَتَيْتَ أَمْرًا أَكْرَهَ عِنْدَنَا مِنْ إِسْرَاعِكَ فِي هَذَا الأَمْرِ مُنْذُ أَسْلَمْتَ. فَقَالَ عَمَّارٌ مَا رَأَيْتُ مِنْكُمَا مُنْذُ أَسْلَمْتُمَا أَمْرًا أَكْرَهَ عِنْدِي مِنْ إِبْطَائِكُمَا عَنْ هَذَا الأَمْرِ. وَكَسَاهُمَا حُلَّةً حُلَّةً، ثُمَّ رَاحُوا إِلَى الْمَسْجِدِ.
Bukhari
Afflictions and the End of the World • Hadith 53