Exodus 23:19

ראשית בכורי אדמתך THE FIRST OF THE FIRST-FRUITS OF THY GROUND [THOU SHALT BRING etc.] — Even in the seventh year the offering of the first fruits is obligatory in some cases, therefore here also (where Scripture mainly deals with the laws of the Sabbatical year) it is stated: “the first of the first-fruits of thy land [shalt thou bring, etc.]”. How was the procedure at the setting apart of the first fruits? A man goes into his field and sees a fig which was the first to ripen; he ties a piece of reed-grass round it to distinguish it and so marks its sacred character (Mishnah Bikkurim 3:1). The law of the first fruits applies only to the seven kinds of produce that are mentioned in Scripture: (Deuteronomy 8:8) “a land of wheat and barley etc.”, for which Palestine is praised in that verse (Mishnah Bikkurim 3:1). לא תבשל גדי THOU SHALT NOT COOK A KID — A calf and a lamb also are comprehended under the term גדי, for גדי means nothing more than a young tender animal, as you may gather from the fact that you will find in several passages in the Torah that the term גדי is used and that the writer felt it necessary specially to explain it by adding after it the word עזים, as, e. g., (Genesis 38:17) “I will send forth a גדי of the goats”; (Genesis 38: 20) “the גדי of the goats”; (Genesis 27:9) “two kids of the goats (גדיי עזים)”. This fact serves to show you that wherever גדי is mentioned without further description the term implies also a calf and a lamb. — In three different passages the law לא תבשל גדי is written: once for the purpose of prohibiting the eating of meat-food with milk-food, once to prohibit us from deriving any other benefit (besides eating) from such mixture, and once to prohibit the boiling of meat with milk (Mekhilta; Chullin 115b).

רֵאשִׁ֗ית בִּכּוּרֵי֙ אַדְמָ֣תְךָ֔ תָּבִ֕יא בֵּ֖ית יְהֹוָ֣ה אֱלֹהֶ֑יךָ לֹֽא־תְבַשֵּׁ֥ל גְּדִ֖י בַּחֲלֵ֥ב אִמּֽוֹ׃ {פ}

The first of the firstfruits of thy land thou shalt bring to the house of the Lord thy God. Thou shalt not boil a kid in its mother’s milk.