Musnad Ahmad 482:140

Harun ibn Ma'ruf and Surayj narrated to us, they said: Ibn Wahb narrated to us. Surayj said: From 'Amr. Harun said: 'Amr ibn al-Harith informed me, from Abu 'Ali Thumamah ibn Shafi', that he heard 'Uqbah ibn 'Amir saying: I heard the Messenger of Allah, peace and blessings of Allah be upon him, saying while he was on the pulpit: "{And prepare against them whatever you are able of power} [Al-Anfal: 60]. Verily, the power is archery. Verily, the power is archery. Verily, the power is archery."