All the firstling males that come of thy herd and of thy flock thou shalt sanctify unto the LORD thy God: {h} thou shalt do no work with the firstling of thy bullock, nor shear the firstling of thy sheep.

(h) For they are the Lords.

Wesley's Notes

15:19 All the firstling males thou shalt sanctify - Giving them to God on the eighth day. And thou shalt do no work with the female firstlings of the cow, nor shear those of the sheep. Even these must be offered to God as peace - offerings, or used in a religious feast.

Jamieson-Fausset-Brown Bible Commentary

19. All the firstling males of thy herd and of thy flock thou shalt sanctify unto the Lord thy God-[See on [143]Ex 13:2]; see Ex 22:30).

thou shalt do not work with the firstling of thy bullock-that is, the second firstlings (see De 12:17, 18; 14:23).

Matthew Henry's Concise Commentary

15:19-23 Here is a direction what to do with the firstlings. We are not now limited as the Israelites were; we make no difference between a first calf, or lamb, and the rest. Let us then look to the gospel meaning of this law, devoting ourselves and the first of our time and strength to God; and using all our comforts and enjoyments to his praise, and under the direction of his law, as we have them all by his gift.

Matthew Henry's Whole Bible Commentary

Verses 19-23

Here is, 1. A repetition of the law concerning the firstlings of their cattle, that, if they were males, they were to be sanctified to the Lord (v. 19), in remembrance of, and in thankfulness for, the sparing of the first-born of Israel, when the first-born of the Egyptians, both of man and beast, were slain by the destroying angel (Ex. 13:2, 15); on the eighth day it was to be given to God (Ex. 22:30), and to be divided between the priest and the altar, Num. 18:17, 18. 2. An addition to that law, for the further explication of it, directing them what to do with the firstlings, (1.) That were females: "Thou shalt do no work with the female firstlings of the cow, nor shear those of the sheep" (v. 19); of them the learned bishop Patrick understands it. Though the female firstlings were not so entirely sanctified to God as the males, nor so early as at eight days old, yet they were not to be converted by the owners to their own use as the other cattle, but must be offered to God as peace-offerings, or used in a religious feast, at the year's end, v. 20. Thou shalt eat it before the Lord thy God, as directed ch. 12:18. (2.) But what must they do with that which was blemished, ill-blemished? v. 21. Were it male or female, it must not be brought near the sanctuary, nor used either for sacrifice or for holy feasting, for it would not be fit to honour God with, nor to typify Christ, who is a Lamb without blemish; yet it must not be reared, but killed and eaten at their own houses as common food (v. 22), only they must be sure not to eat it with the blood, v. 23. The frequent repetition of this caution intimates what need the people had of it, and what stress God laid upon it. What a mercy it is that we are not under this yoke! We are not dieted as they were; we make no difference between a first calf, or lamb, and the rest that follow. Let us therefore realize the gospel meaning of this law, devoting ourselves and the first of our time and strength to God, as a kind of first-fruits of his creatures, and using all our comforts and enjoyments to his praise and under the direction of his law, as we have them all by his gift.