Musnad Abu Ya'la al-Mawsili 147:9

Abu Khaythama narrated to us, Ismail narrated to us, from Ayyub, from Humayd ibn Hilal, from Anas ibn Malik, who said: The Messenger of Allah (ﷺ) said: "Zayd took the banner and was struck down. Then Ja'far took it and was struck down. Then Abdullah ibn Rawahah took it and was struck down. Then Khalid ibn al-Walid took it without being appointed, and Allah granted him victory. And it does not please them—or it does not please me—that they are with us." And his eyes were shedding tears.