"Do not boil a goat in its mother's milk" -Deuteronomy 14:21.
I remember the first time I read this verse in an Old Testament course in college, a long time ago. It struck me as very odd.
Another one was, "If you come across a bird’s nest in any tree or on the ground, with young ones or eggs and the mother sitting on the young or on the eggs, you shall not take the mother with the young" (Deuteronomy 22:6).
Why, I wondered, would God put in His Scriptures such commandments about what we might have for dinner? And it has taken until now, my mature years, to understand what seems so plain now.
There are many passages in Scripture that show God's concern for the family. They start with the creation mandate in Genesis 1:28: "God said to them [i. e., Adam and Eve], 'Be fruitful and multiply and fill the earth and subdue it, and have dominion over the fish of the sea and over the birds of the heavens and over every living thing that moves on the earth.'" The welfare of the family is the concern of the Fifth and Seventh Commandments, and of such extended portions of Scripture as Ephesians 5:22-33.
The two verses from Deuteronomy above reflect that concern. Notice that the command is not to avoid cooking a kid in milk, or to avoid eating eggs. In both cases the restriction is against the relationship between the animal mother and her offspring. The perpetuation of life is precious to God, both for mankind and for the animals.
The reason that this has become clear to me in the past few years is because I have become more involved in the fight against human sacrifice in America, nicknamed euphemistically as "abortion." When a baby is aborted, that is the new generation murdered not just with his mother, as in the animal texts of Deuteronomy, but by his mother. What can more destroy the family than does mothers, often with the concurrence of fathers, who kill their preborn children.