Al-Kāfi - Volume 3 > Sprucing up on Fridays
Hadith #7

7ـ مُحَمَّدُ بْنُ إِسْمَاعِيلَ عَنِ الْفَضْلِ بْنِ شَاذَانَ عَنِ ابْنِ أَبِي عُمَيْرٍ عَنْ حَفْصِ بْنِ الْبَخْتَرِيِّ عَنْ أَبِي عَبْدِ الله (عَلَيْهِ الْسَّلام) قَالَ أَخْذُ الشَّارِبِ وَالأظْفَارِ مِنَ الْجُمُعَةِ إِلَى الْجُمُعَةِ أَمَانٌ مِنَ الْجُذَامِ.

7. Muhammad ibn ’Isma‘il has narrated from al-Fadl ibn Shadhan from ibn abu ‘Umayr from Hafs ibn al-Bakhtariy who has said the following: “Abu ‘Abd Allah, ‘Alayhi al-Salam, has said, ‘Trimming one’s mustache, and fingernails every Friday is protection against leprosy.’”