It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that a man asked the Prophet (peace and blessings be upon him): "O Messenger of Allah! When we assume Ihram, which clothes can we wear?" The Prophet (peace and blessings be upon him) said: "A person in Ihram must not wear a shirt, trousers, turban, or leather socks, except if he cannot find sandals. Whoever cannot find sandals should cut the leather socks below the ankles and wear them. Likewise, a cap or any cloth dyed with wars (a kind of grass) or saffron must also not be worn by a person in Ihram."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 5472
Hadith Gradingحکم دارالسلام:إسناده صحيح ، خ :5794.