Or HaChaim on Exodus 23:19/אור החיים על שמות כ״ג:י״ט

1 ראשית בכורי אדמתך, "The choicest first-fruits of your soil, etc." Perhaps the Torah hints here that one must not destroy one's seed (semen) and that the son born of one's first seminal emission should be dedicated to the service of the Lord (compare Yuma 2 according to which the word ביתו is an oblique reference to one's wife)

2The Torah emphasises "the house of the Lord your G'd," to exclude that such a son be brought to a brothel. Jacob performed this commandment as he said of himself when blessing Reuven: "you are my strength and the first fruit of my virility" (Genesis 49,3).

3The conclusion of our verse in which the Torah directs us not to boil the kid in the milk of its mother contains another important moral/ethical lesson. When a man deliberately destroys his semen he is the cause of infants dying while they still suckle at the breast of their mother. I have explained this matter in connection with Michah 6,7: "Shall I give my first-born for my transgression, the fruit of my body for my sins?" When man destroys his semen he creates a destructive force. This destructive force gains control later over a son who is born to such a father. The souls of such children are considered as עשוקות, "oppressed or deprived," as explained in the Zohar volume one page 219. The reason for this is that their father failed to dedicate his first emission of semen for the creation of a life devoted to the service of the Lord.

4According to the opinion that the legislation of mixing milk and meat results in a prohibition of any benefit from such a mixture, this would explain why this legislation adjoins that of the bringing of the first-fruits to the Temple seeing that such first-fruits are also totally prohibited to their owner (compare Chulin 114 and Maimonides Hilchot Bikkurim 2, who declares that one must not use בכורים which have become ritually defiled for heating the stove). I have written more about this in my book פרי תואר.