From Sahih Muslim (Hadith 5429):
Anas b. Malik reported to them (his companions) that Allah's Messnger (ﷺ) had granted concession to Abd al-Rahman b. *Anf and Zubair b. 'Awwam for the wearing of a silk shirt during the journey and because of itch which they both had or any other disease from which both of them had been suffering
Reference: Muslim 5429