Bakr bin 'Abdullah Al-Muzani said: "Anas said: “I heard the Prophet reciting the Talbiyah for 'Umrah and Hajj together. I told Ibn 'Umar about that and he said: "He recited the Talbiyah for Hajj only. I met Anas and told him what Ibn 'Umar had said, and Anas said: "do you think of us as no more than children? I heard the Messenger of Allah say: “Labbaika 'Umratan wa Hajjan ma'an (Here I am (O allah) for 'Umrah and Hajj together) (sahih)””"
SahihSahihSahih - Agreed UponBook 24 · Hadith 113