Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said that Sayyiduna Dhu'ayb (may Allah be pleased with him) informed him that the Prophet (peace and blessings be upon him) sent two camels for sacrifice with him and ordered: "If they are about to perish, slaughter them, dye the sandals of both (i.e. those hung as a garland) in their blood and place them on their necks. Leave it to the people; do not give any order about it, and neither you yourself nor those with you are to eat anything from it."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 10250