(78) باب التَّحْرِيضِ عَلَى الرَّمْىِ
Narrated Salama bin Al-Akwa`:
The Prophet (ﷺ) passed by some people of the tribe of Bani Aslam who were practicing archery. The Prophet said, "O Bani Isma`il ! Practice archery as your father Isma`il was a great archer. Keep on throwing arrows and I am with Bani so-and-so." So one of the parties ceased throwing. Allah's Apostle said, "Why do you not throw?" They replied, "How should we throw while you are with them (i.e. on their side)?" On that the Prophet (ﷺ) said, "Throw, and I am with all of you."
Reference: Sahih al-Bukhari 2899
In-book reference: Book 56, Hadith 113
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 4, Book 52, Hadith 148