Sahih Bukhari Volume 007, Book 072, Hadith Number 696.

Narrated By Abdullah : A man got up and said, O Allah's Apostle! What do you order us to wear when we assume the state of Ihram?" The Prophet replied, "Do not wear shirts, trousers, turbans, hooded cloaks or Khuffs, but if a man has no sandals, he can wear Khuffs after cutting them short below the ankles; and do not wear clothes touched with (perfumes) of saffron or wars."