Good Manners and Form (Al-Adab)

Bukhari :: Book 8 :: Volume 73 :: Hadith 239

Narrated 'Abdullah bin Mughaffal Al-Muzani:

The Prophet forbade the throwing of stones (with the thumb and the index or middle finger), and said "It neither hunts a game nor kills (or hurts) an enemy, but it gouges out an eye or breaks a tooth."