Musannaf Ibn Abi Shayba 18:353

Abu Bakr narrated to us, he said: Abd al-Rahim narrated to us, from Hajjaj, from Amr ibn Shu'ayb, from Sa'id ibn al-Musayyib: That a group of people were shooting, and a man among them shot an arrow by mistake, and it struck the stomach of a man and passed through to his back. He was treated and recovered. The matter was raised to Abu Bakr, and he judged regarding it [the compensation] as two *ja'ifah* wounds.