John Calvin Commentary Leviticus 22:28

"And whether it be cow or ewe, ye shall not kill it and its young both in one day." — Leviticus 22:28 (ASV)

And whether it be a cow or ewe. Though cruelty was indeed condemned in this precept, still I have no doubt that Moses speaks primarily of the sacrifices. I confess the word שחט, shachat, which he uses, is a general one. However, since throughout the chapter he is specifically addressing the sacrifices, and in connection with these words adds the conclusion respecting the hallowing of His holy name (Leviticus 22:32), the context requires that we consider it to be an instruction for purity in God’s service.

If anyone prefers to extend it further, I will not contest the point; in that case, this sentence would be a supplement to the Sixth Commandment. I have, however, followed what appears most probable, and the reader of sound judgment will, I hope, agree with me.

Meanwhile, I confess that all barbarity and cruelty were therefore prohibited in the sacrifices, and in them the rule was laid down that men should not be cruel concerning their daily food. It is a sight not at all pleasant to gentle minds to see the dam killed together with her young; and, if it were a common custom, men would easily become callous towards bloodshedding in general. God would therefore not have religious practices disconnected from the duties of humanity; and the tendency of the precept is that God’s altar should not be a Cyclopean slaughter-house.