Fiqh-us-Sunnah Volume 5, Hajj and ‘Umrah, Fiqh 5.032.

This consists of two sheets of cloth. One of these is wrapped round the upper part of the body, except the head, and the other (izar) is wrapped round the lower part of the body. Both of these sheets should be white as this colour is the best colour in the sight of Allah.

Ibn ‘Abbas said: “Allah’s Messenger (peace be upon him) combed his hair, wore some perfume, put on his Hajj garb, along with his Companions, and then he set out from Madinah accompanied by them.” (Reported by sukhari)