Leviticus 3:17

17. ye eat neither fat nor blood--The details given above distinctly define the fat in animals which was not to be eaten, so that all the rest, whatever adhered to other parts, or was intermixed with them, might be used. The prohibition of blood rested on a different foundation, being intended to preserve their reverence for the Messiah, who was to shed His blood as an atoning sacrifice for the sins of the world [Brown].

Robert Jamieson, A. R. Fausset & David Brown, 1871 · public domain

Verse 17 That ye eat neither fat nor blood - It is not likely that the fat should be forbidden in the same manner and in the same latitude as the blood. The blood was the life of the beast, and that was offered to make an atonement for their souls; consequently, this was never eaten in all their generations: but it was impossible to separate the fat from the flesh, which in many parts is so intimately intermixed with the muscular fibres; but the blood, being contained in separate vessels, the arteries and veins, might with great ease be entirely removed by cutting the throat of the animal, which was the Jewish method. By the fat therefore mentioned here and in the preceding verse, we may understand any fat that exists in a separate or unmixed state, such as the omentum or caul, the fat of the mesentery, the fat on the kidneys, and whatever else of the internal fat was easily separable, together with the whole of the tail already described. And probably it was the fat of such animals only as were offered to God in sacrifice, that was unlawful to be eaten. As all temporal as well as spiritual blessings come from God, he has a right to require that such of them should be dedicated to his service as he may think proper to demand. He required the most perfect of all the animals, and the best parts of these perfect animals. This he did, not that he needed any thing, but to show the perfection of his nature and the purity of his service. Had he condescended to receive the meanest animals and the meanest parts of animals as his offerings, what opinion could his worshippers have entertained of the perfection of his nature? If such imperfect offerings were worthy of this God, then his nature must be only worthy of such offerings. It is necessary that every thing employed in the worship of God should be the most perfect of its kind that the time and circumstances can afford. As sensible things are generally the medium through which spiritual impressions are made, and the impression usually partakes of the nature of the medium through which these impressions are communicated; hence every thing should not only be decent, but as far as circumstances will admit dignified, in the worship of God: the object of religious worship, the place in which he is worshipped, and the worship itself, should have the strongest and most impressive correspondence possible.

Adam Clarke, 1831 · public domain