It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that once the Prophet (peace and blessings be upon him) sent a man somewhere, giving him eighteen camels and instructing him with what he needed to do. The man left, but after a short while, he returned and said, "Please tell me, if any of these camels becomes exhausted, what should I do?" The Prophet (peace and blessings be upon him) said: "Slaughter it, soak its shoe in its blood, then apply it to its chest, but neither you nor any of your companions should eat its meat."
Hadith Referenceمسند احمد / ومن مسند بني هاشم / 1869