Sahih Bukhari, Chapter: Minor Pilgrimage (Umra)

We set out along with Allah's Apostle shortly before the appearance of the new moon (crescent) of the month of Dhi-l-Hijja and he said to us, "Whoever wants to assume Ihram for Hajj may do so; and whoever wants to assume Ihram for 'Umra may do so. Hadn't I brought the Hadi (animal for sacrificing) (with me), I would have assumed Ihram for Umra." ('Aisha added,): So some of us assumed Ihram for Umra while the others for Hajj. I was amongst those who assumed Ihram for Umra. The day of Arafat approached and I was still menstruating. I complained to the Prophet (about that) and he said, "Abandon your Umra, undo and comb your hair, and assume Ihram for Hajj;." When it was the night of Hasba, he sent Abdur Rahman with me to At-Tanim and I assumed Ihram for 'Umra (and performed it) in lieu of my missed Umra.