Leviticus 27:33

He shall not search whether it be good or bad,.... In a good or bad state of health, fat or lean, perfect or blemished, but take it as it is, be it what it will:

neither shall he change it; neither for the better nor the worse, no alteration was to be made, but the beast was to be taken as it came:

and if he change it at all, then both it and the change shall be holy; be sacred to the Lord, and for his use and service; this was done to restrain men from making any alteration, since if they did, both the one and the other were taken from them; yea, were to be beaten with forty stripes, save one b; whether this change was of the herd with the flock, or of the flock with the herd; or of lambs with goats, or goats with lambs; or of males with females, or of females with males; or of perfect with blemished ones, or of blemished ones with perfect ones:

it shall not be redeemed; from whence the Jews c gather, that a tithe beast was not to be bought and sold, whether blemished or unblemished.

b Misnah Temurah, c. 1. sect. 1, 2. c Maimon. Hilchot Becorot, c. 6. sect. 5, 6.