The Book Pertaining to Clothes and Decoration (Kitab Al-Libas wa'l-Zinah)
Muslim :: Book 24 : Hadith 5172
Anas b. Malik reported that 'Abd al-Rahman b. Auf and Zu'bair. b. 'Awwam complained to Allah's Messenger (may peace be upon him) about lice; he granted them concession to wear shirts of silk.