Also you shall take of the ram the fat and the fat tail, and the fat that covers the entrails, and the fat above the liver, and the two kidneys, and the fat that is upon them, and the right shoulder; for it is a ram of consecration:
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George Leo Haydock
Rump, or tail, for which the sheep of Arabia were famed; some having tails three yards long, others a yard thick. (Herodotus, iii. 113.) They weighed from 12 to 30 pounds, and were almost all fat. (Calmet)
Therefore by divine ordinance the priest receives a shoulder for sacrifice, and that too the right one and separate. His conduct should be not only profitable but also outstanding. He should not only do what is upright in the midst of the wicked but also surpass the welldoers among his subjects. And as he surpasses them in the dignity of his rank, so should he in the virtue of his conduct.