Al-Kāfi - Volume 6 > The Ornaments
Hadith #5

عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ أَبِيهِ عَنِ ابْنِ أَبِي عُمَيْرٍ عَنْ عَبْدِ اللَّهِ بْنِ سِنَانٍ عَنْ أَبِي عَبْدِ اللَّهِ ( عليه السلام ) قَالَ لَيْسَ بِتَحْلِيَةِ السَّيْفِ بَأْسٌ بِالذَّهَبِ وَ الْفِضَّةِ .

5. Ali ibn Ibrahim has narrated from his father from ibn abu ‘ Umayr from ‘Abd Allah ibn Sinan who has said the following: “Abu ‘Abd Allah, ‘Alayhi al-Salam, has said, ‘It is not unlawful to decorate the sword with gold and silver.’”