Musnad Ahmad 28:163

Hassan narrated to us, Ibn Lahi'ah narrated to us, Huyayy ibn Abdullah narrated to us, from Abu Abd al-Rahman al-Hubuli, from Abdullah ibn Amr, who said: Hamza ibn Abd al-Muttalib came to the Messenger of Allah, peace and blessings of Allah be upon him, and said: "O Messenger of Allah, appoint me to something by which I may live." The Messenger of Allah, peace and blessings of Allah be upon him, said: "O Hamza, is a soul that you give life to more beloved to you, or a soul that you cause to die?" He said: "Rather, a soul that I give life to." He said: "Then attend to your own soul."