Musannaf Ibn Abi Shayba 36:446

'Abd al-Rahim ibn Sulayman narrated to us, from Hisham ibn 'Urwah, from his father, that the Messenger of Allah (may Allah bless him and grant him peace) dispatched an expedition before Mu'tah and appointed Usamah ibn Zayd as their commander. Among that expedition were Abu Bakr and 'Umar. He said: Some people among the people were criticizing that, regarding the Messenger of Allah (may Allah bless him and grant him peace) appointing Usamah over them. He said: The Messenger of Allah (may Allah bless him and grant him peace) stood up and addressed the people, then said: "Indeed, some people among you have criticized me regarding the appointment of Usamah, and they only criticized the appointment of Usamah just as they criticized the appointment of his father before him. By Allah, he was indeed worthy of the command, and he was indeed among the most beloved of people to me. And his son is indeed among the most beloved of people to me after him, and I hope that he will be among your righteous ones, so treat him well."