Fighting for the Cause of Allah (Jihaad)
حَدَّثَنَا أَحْمَدُ بْنُ مُحَمَّدٍ، أَخْبَرَنَا عَبْدُ اللَّهِ، أَخْبَرَنَا الأَوْزَاعِيُّ، قَالَ سَمِعْتُ سُلَيْمَانَ بْنَ حَبِيبٍ، قَالَ سَمِعْتُ أَبَا أُمَامَةَ، يَقُولُ لَقَدْ فَتَحَ الْفُتُوحَ قَوْمٌ مَا كَانَتْ حِلْيَةُ سُيُوفِهِمِ الذَّهَبَ وَلاَ الْفِضَّةَ، إِنَّمَا كَانَتْ حِلْيَتُهُمُ الْعَلاَبِيَّ وَالآنُكَ وَالْحَدِيدَ.Narrated Abu Umama:Some people conquered many countries and their swords were decorated neither with gold nor silver, but they were decorated with leather, lead and iron
From Sahih al-Bukhari, whose reports the scholars accept as authentic.