Sahih Muslim Book 7, Hadith Number 2653.

Chapter : What is permitted for the Muhrim (wearer of Ihram) in Hajj and Umra, what is not permissible and forbiddance of the use of perfume.

Jabir (Allah be pleased with him) reported Allah’s Messenger (may peace be upon him) as saying: He who does not find shoes to wear may wear socks, and he who does not find lower garment to wear may put on trousers.