Musa bin Salamah al-Hudhali (may Allah have mercy on him) said: Sinan bin Salamah (may Allah have mercy on him) and I both set out for Umrah. Sinan set out taking his (sacrificial camel) with him. The sacrificial camel became exhausted from the journey, and he became very worried about its condition: if it gave out, how would he bring it along? He said: If I reach the city, I will make thorough inquiries about this myself. He said: When we came to the valley of al-Batha', Musa bin Salamah said: Let us go to Abdullah bin Abbas (may Allah be pleased with them both) and tell him what happened to us. Musa said: Sinan told him the story of his sacrificial camel, and he said: You have asked one who knows the matter well. The Prophet (peace and blessings be upon him) sent 16 sacrificial camels with a man and gave him instructions concerning them. He set off, then came back and said: O Messenger of Allah! If one of the animals becomes exhausted, what should I do? He (peace and blessings be upon him) said: "Slaughter it, then dye its sandals (hung as a garland) in its blood and place them on its neck. Neither you nor any of your companions may eat from it."
(b) Musaddad narrates from Abd al-Warith that there were 18 sacrificial camels, and this is correct.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 10248