Narrated Ibn `Abbas: The Prophet (peace be upon him) delivered a sermon at `Arafat and said, “Whoever does not get an Izar can wear trousers, and whoever cannot get a pair of shoes can wear Khuffs (socks made from thick fabric or leather).”
28 Penalty of Hunting while on Pilgrimage
Hadith number 1843
Volume no 3
Chapter: 16 (If an Izar is not available, one can wear trousers)