וְדֵ֤י ׀ חֲלֵ֬ב עִזִּ֗ים לְֽ֭לַחְמְךָ לְלֶ֣חֶם בֵּיתֶ֑ךָ וְ֝חַיִּ֗ים לְנַעֲרוֹתֶֽיךָ׃
И будут козы'молока достаточно для еды твоей, для еды твоего дома; И обслуживание для твоих девиц.
Haamek Sheilah
After which the Prophet continues, “To whom is He teaching knowledge?” (this pertains to the judges) “and to whom is he imparting wisdom?”10Verse 9. (to whom, meaning those who debate and refute arguments at the gate of the academy). “To those just weaned from milk,”11Verse 9. (for there were many Jews in Isaiah’s time who were accustomed to eating dairy foods; as Solomon stated in Proverbs, “There will be enough goats’ milk for your food, for the food of your household, and life [sustenance] for your maidens.”1227:27. [A further proof that dairy products, rather than meat, were their main staple], can also be seen in Tractate Hullin in the chapter entitled Kissui ha-dam,1384a. “‘…will ensnare,’14Lev. 17:13. teaches us that one should not eat meat except after much preparation.”15See Rashi: one should not accustom himself to eat meat at all meals. Rather, it should be a luxury that requires special preparation. Since the [people at that time] were in excellent health, it was proper for a Talmud scholar to reduce his food intake even of dairy foods. As it is taught in a mishnah in [Avos], “This is the way of Torah: Eat bread with salt, [drink water in small measure],” etc.16Avos 6:4. Isaiah [also] directed this admonition [against excessive indulgences] towards those “weaned” from dairy foods. [For if a Talmud scholar conducts his life in such a manner], he will then have the ability to make rulings and understand legal discussions. One can also add in homiletic fashion [that the phrase, “weaned from milk,” is referring to Talmudic scholars].
Rashbam
לא תבשל גדי בחלב אמו, it is usual for goats to give birth to two kids at the same time, and it was customary for people to slaughter one of them right away. Seeing that mother goats have an abundance of milk (expecting to nurse at least two young kids) they used the excess milk to boil the young kid in after it had been slaughtered. (Proverbs 27,27 “the goat’s milk will suffice for your food, the food of your household and the maintenance of your maids.”) It is something distasteful, revolting, something akin to gluttony, to consume the mother’s milk together with the young animal that this milk was intended to nourish. We find a parallel in the legislation not to slaughter mother animal and her young on the same day, as well as the prohibition not to take the young chicks while the mother bird is present. (Leviticus 22,25 and Deuteronomy 22,6-7) The Torah teaches you these matters as a matter of elementary culture, i.e. respecting life. Seeing that on the festivals many animals are consumed, the Torah included this legislation in the paragraph dealing with other aspects of these festivals. If the consuming of these animals is prohibited under such circumstances, how much more so are mixture of milk and meat prohibited as discussed in Chulin 113.