Musnad Abu Ya'la al-Mawsili 143:4

Abu Khaythama narrated to us, Sa'id bin 'Amir narrated to us, from Habib bin al-Shahid, from Bakr bin 'Abd Allah, from Anas bin Malik: That the Messenger of Allah (ﷺ) entered into the state of Ihram for both of them [Hajj and 'Umrah] together. He [the narrator] said: So I mentioned that to Ibn 'Umar, and he said: "He entered into the state of Ihram for Hajj." So I mentioned that to Anas, and he said: "You do not consider us to be anything but children."