Shama-il Tirmidhi Chapter 8, Hadith Number 16 (68).
Mughirah bin Shu’bah (R.A) says: “Rasulullah (S.A.W) wore a rumi Jubbah which had narrow sleeves.”
This incident was at the time of Ghazwah Tabuk. The ‘Ulama have interpreted from this hadith that a thing made by non-believers is not najis (na-paak) till we can outwardly find of this. Upto that time there were no Muslims in Rome, and Sayyidina Rasulullah (S.A.W) wore the clothing made by them.