Volume 1, Book 3, Number 136:

Narrated Ibn 'Umar: A man asked the Prophet : "What (kinds of clothes) should a Muhrim (a Muslim intending to perform 'Umra or Hajj) wear? He replied, "He should not wear a shirt, a turban, trousers, a head cloak or garment scented with saffron or Wars (kinds of perfumes). And if he has n slippers, then he can use Khuffs (leather socks) but the socks should be cut short so as to make the ankles bare." (See Hadith No. 615, Vol. 2).