Musnad Ahmad 33:371

Hashim ibn al-Qasim narrated to us, Isra'il narrated to us, from Jabir, from 'Amir, from Jabir ibn 'Abdullah, who said: A young man from Banu Salamah came to the Prophet, peace and blessings of Allah be upon him, and said: "I saw a rabbit and I threw [a stone] at it, and I did not have any iron with me to slaughter it with, so I slaughtered it with a flint stone." The Prophet, peace and blessings of Allah be upon him, said to him: "Eat."