Musannaf Ibn Abi Shayba 35:289

Hafs narrated to us, from Layth, from Mujahid, from Umar, who said: Whoever designates a sacrificial animal as a voluntary offering, and it becomes incapacitated, he shall slaughter it before reaching the Sacred Precinct (al-Haram). He shall not eat from it. And if he eats from it, he is liable for a replacement.