From Sahih Bukhari (Hadith 3373):
Narrated Salama bin Al-Akwa`:The Prophet (ﷺ) passed by some persons of the tribe of Aslam practicing archery (i.e. the throwing of arrows) Allah's Messenger (ﷺ) said, "O offspring of Ishmael! Practice archery (i.e. arrow throwing) as your father was a great archer (i.e. arrow-thrower). I am with (on the side of) the son of so-and-so-." Hearing that, one of the two teams stopped throwing. Allah's Messenger (ﷺ) asked them, ' Why are you not throwing?" They replied, "O Allah's Messenger (ﷺ)! How shall we throw when you are with the opposite team?" He said, "Throw, for I am with you all
Reference: Bukhari 3373