From Sahih Muslim (Hadith 2984):
Hafsa (Allah be pleased with her), the wife of Allah's Apostle (ﷺ), said:Messenger of Allah. what about people who have put off Ihram whereas you have not put it off after your 'Umra? He said: I have stuck my hair and have driven my sacrificial animal, and would not, therefore, put off Ihram until I have sacrificed the animal
Reference: Muslim 2984