Lady Hafsa (may Allah be pleased with her), the wife of the Messenger of Allah (ﷺ), says: I asked the Messenger of Allah (ﷺ): What is the matter that people have become halal (come out of ihram) after performing Umrah, but you have not become halal? He (ﷺ) replied: "I have applied talbeed (plastering) to my hair and have brought the sacrificial animal with me, so I cannot come out of ihram before offering the sacrifice."
Hadith Referenceالسنن المأثورة / باب ما جاء في فدية الأذى / 472
Hadith Takhrijصحیح بخاری، الحج، باب التمتع والاقران والافراد فی الحج، رقم: 1566، صحیح مسلم، الحج، باب القارن لا ینحل الا فی وقت تحلل ...... الخ، رقم: 1229۔