Musnad Ahmad 27:1543

Hashim ibn al-Qasim narrated to us, Layth narrated to us, Nafi’ narrated to me, from Abdullah, that he said: A man stood up and said: "O Messenger of Allah, what do you command us to wear of clothing while in Ihram?" The Messenger of Allah, peace and blessings of Allah be upon him, said to him: "Do not wear shirts, nor trousers, nor turbans, nor hooded cloaks (burnus), nor leather socks, unless one does not have sandals, then let him wear the leather socks, provided they are cut below the ankles. And do not wear anything of clothing that has been touched by wars (a type of dye) or saffron. And the woman in Ihram shall not wear a niqab (face veil), nor shall she wear gloves."