Abdullah bin Umar (may Allah be pleased with them) narrates from Lady Hafsa (may Allah be pleased with her) that she said: "O Messenger of Allah (ﷺ)! What is the matter with the people that they have ended their ihram after performing ‘Umrah, but you have not ended your ihram after your ‘Umrah?" So the Prophet (ﷺ) said: "I have stuck my hair (with gum) and put a garland on my sacrificial animal, so I will not end my ihram until I have slaughtered my sacrifice."
Hadith Referenceمسند الإمام الشافعي / كتاب الحج / 806
Hadith Takhrijاخرجه البخاري، الحج، باب التمتع، والقرآن، والإفراد بالحج وفسخ الحج لمن لم يكن معه هدى، رقم: 1566 ـ ومسلم، الحج، باب بيان أن القارة لا يتحلل الا في وقت تحلل الحاج المفرد، رقم : (1329)۔