Sayyiduna Anas (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) permitted Abd al-Rahman bin Awf and al-Zubayr bin al-Awwam (may Allah be pleased with them both) to wear silk because of itching.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب صلاة الخوف / 6076