Fighting for the Cause of Allah (Jihaad)
حَدَّثَنِي مُحَمَّدُ بْنُ بَشَّارٍ، حَدَّثَنَا غُنْدَرٌ، حَدَّثَنَا شُعْبَةُ، سَمِعْتُ قَتَادَةَ، عَنْ أَنَسٍ، رَخَّصَ أَوْ رُخِّصَ لِحِكَّةٍ بِهِمَا.Narrated Anas:(Wearing of silk) was allowed to them (i.e. `AbdurRahman and Az-Zubair) because of the itching they suffered from
From Sahih al-Bukhari, whose reports the scholars accept as authentic.