Sayyiduna Ibn Umar (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) "forbade the one in ihram from wearing shirts, outer coats (qaba'), trousers and leather socks, but permitted leather socks if sandals cannot be found; nor should he wear a garment touched by wars or saffron."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9063