Sahih Bukhari Volume 001, Book 006, Hadith Number 314.
Narated By 'Aisha : On the 1st of Dhul-Hijja we set out with the intention of performing Hajj. Allah's Apostle said, "Any one who likes to assume the Ihram for 'Umra he can do so. Had I not brought the Hadi with me, I would have assumed the Ihram for 'Umra. "Some of us assumed the Ihram for 'Umra while the others assumed the Ihram for Hajj. I was one of those who assumed the Ihram for 'Umra. I got menses and kept on menstruating until the day of 'Arafat and complained of that to the Prophet. He told me to postpone my 'Umra, undo and comb my hair, and to assure the Ihram of Hajj and I did so. On the right of Hasba, he sent my brother 'Abdur-Rahman bin Abi Bakr with me to At-Tah'im, where I assumed the Ihram for'Umra in lieu of the previous one. Hisham said, "For that ('Umra) no Hadi, fasting or alms were required.