Sayyidah Aishah (may Allah be pleased with her) said: We set out with the Messenger of Allah (peace and blessings be upon him) in the year of the Farewell Hajj and we made the talbiyah for Umrah. Then the Messenger of Allah (peace and blessings be upon him) said: "Whoever has a sacrificial animal with him should make the talbiyah for both Hajj and Umrah, and he should not leave ihram until he leaves it from both of them."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 8775