From Sahih Bukhari (Hadith 5916):
Narrated Hafsa:(the wife of the Prophet) I said, "O Allah's Messenger (ﷺ)! Why have the people finished their Ihram after performing the `Umra while you have not finished your Ihram after your `Umra?" He said, "I have done Talbid (of my hair) and have decorated my Hadis with garlands, so I shall not finish my Ihram till I have slaughtered my Hadi (animal for sacrifice)
Reference: Bukhari 5916