Sahih Bukhari Volume 002, Book 026, Hadith Number 783.
Narated By Ibn 'Umar : Hafsa said, "O Allah's Apostle! What is wrong with the people; they finished their Ihram after performing 'Umra, but you have not finished it after your 'Umra?" He replied, "I matted my hair and have garlanded my Hadi. So, I cannot finish my Ihram till I slaughter (my Hadi). "