Sahih Bukhari Volume 002, Book 026, Hadith Number 633.
Narated By 'Aisha : We set out with Allah's Apostles (to Mecca) in the year of the Prophet's Last Hajj. Some of us had assumed Ihram for 'Umra only, some for both Hajj and 'Umra, and others for Hajj only. Allah's Apostle assumed Ihram for Hajj. So whoever had assumed Ihram for Hajj or for both Hajj and 'Umra did not finish the Ihram till the day of sacrifice. (See Hadith No. 631, 636, and 639).