Musnad Abu Ya'la al-Mawsili 154:183

A man said, while the Messenger of Allah (ﷺ) was on the pulpit, "What should the *muhrim* (pilgrim in the state of ihram) wear?" He said, "He shall not wear the shirt, nor the turban, nor the trousers, nor the hooded cloak (*burnus*), nor the leather socks, unless one does not find sandals, then he may wear what is below the ankles. And he shall not wear anything of the garments that has been touched by *wars* (a yellow dye) or saffron."