John Calvin Commentary Exodus 23:19

"The first of the first-fruits of thy ground thou shalt bring into the house of Jehovah thy God. Thou shalt not boil a kid in it mother`s milk." — Exodus 23:19 (ASV)

You shall not seethe a kid. The threefold repetition of the command reminds us that a serious matter is being addressed, whereas it would be a light and almost frivolous one if, as some suppose, it is merely the prohibition of a somewhat unwholesome food.

But the Jews, not considering its intent, and affecting sanctity, as they do, in trivial, childish practices, dare not taste cheese together with kid or lamb, until they have thoroughly cleaned their teeth. I have no doubt, however, that this prohibition relates to the sacrifices. For in the first passage quoted, it is added in connection with the offering of the first-fruits; and in the second, we read as follows: The first of the first-fruits of your land you shall bring to the house of the Lord your God. Nor shall you seethe a kid in his mother’s milk; and so also in the third passage: You shall not eat of anything that dies of itself, etc., for you are an holy people to the Lord your God; nor shall you seethe a kid in his mother’s milk.

I allow indeed that Moses sometimes mixes together precepts respecting different things, but this running context shows that this precept is delivered among the ceremonies and must therefore be reckoned to be a part of the legal service. From this I conclude, that the people are not only interdicted from eating this sort of food, as if they were to partake of flesh steeped in blood, but that they should not pollute the sacrifices by the carnal mixture.

It is however probable, that meat seasoned with milk was considered a delicacy; but since they might grow cruel if they ate a lamb or kid in its mother’s milk, God forbade offering to Himself what was not allowable even in their common meals. The explanation of some, that kids were excluded from their tables until they were weaned, is not reasonable, because they then begin to have a goatish flavor. But the reason is a very appropriate one, i.e., that God would not permit a monstrous thing in His sacrifices: that the flesh of the young should be cooked in its mother’s milk, and thus, as it were, in its own blood.