In Vayikra 22:26-27 we read:
An ox, lamb or goat, when it is born, shall be with its mother for seven days. From the eighth day and thereafter it may be favorably accepted as a sacrifice as a fire offering to God. An ox or a lamb, it and its offspring, you shall not slaughter in one day.
In Dvarim 22:6-7, we have a related law:
If a bird’s nest happens to be before you on the road, on any tree or on the ground- young birds or eggs- and the mother is roosting on the young birds or on the eggs, you shall not take the mother with the young. You shall surely send away their mother and take the young for yourself, so that it will be good for you and prolong your days.
The reason for the prohibition of the two commandments- the sending away of the mother bird and the slaughtering of the mother and the young on the same day – is to eradicate cruelty and pitilessness from man’s heart…to cultivate in us the quality of mercy, that we may not become cruel, for cruelty envelops the entire personality of man, as is well known from the professional animal killers who often become hardened to human suffering.
Nechama Leibowitz points out:
Indeed, cruelty is indivisible, and once practiced on certain objects, it soon expands. The rule that once free reign has been given by man himself to the demon of destruction (man’s cruel destructive instinct), it does not distinguish between the righteous and the wicked, in our case, between animals and human beings.
We learn in Vayikra Rabba 27:11:
Rabbi Berakya said in the name of Rabbi Levi: It is stated (Mishlei 12:10) “The righteous man regards the life of his beast, but the mercies of the wicked are cruel.” “The righteous man” refers to God, as it says in the Torah (Vayikra 22:26) “An ox, lamb or goat, when it is born, shall be with its mother for seven days” and also (Vayikra 26:27) “An ox or a lamb, it and its offspring, you shall not slaughter in one day.” This teaches us to even have mercy on an animal that is about to be eaten. “The mercies of the wicked are cruel” refers to the wicked Haman as it says (Ester 3:13) “…to destroy, to slay and to exterminate all Jews, young and old, children and women, in a single day…” Haman wanted to kill the youngest of children, even those who had not yet lived for seven days. He also wanted to kill women and their children on the same day- two cruel acts together.
One explanation for the laws above is to teach us to be merciful like God and to stay far away from the wicked behavior of the cruel enemies of the Jewish people such as Sancheriv, Haman and Hitler who had no problem killing babies and mothers with their children.
May our cruel enemies see the light and cease to attack us.