John Calvin Commentary Deuteronomy 22:6

"If a bird`s nest chance to be before thee in the way, in any tree or on the ground, with young ones or eggs, and the dam sitting upon the young, or upon the eggs, thou shalt not take the dam with the young:" — Deuteronomy 22:6 (ASV)

Since by this precept God instructed His people in the law of kindness, it is a supplement to the Sixth Commandment.

Indeed, regard was given to the preservation of the breed; but, additionally, when birds are nesting, since they are very lean, it is certain that they are not wholesome food. Still, there is no question that it was God’s intention to accustom His people to cultivate humaneness.

For, if there is even one drop of compassion in us, it will never enter our minds to kill a poor little bird that burns so intensely—either with the desire for offspring or with love for its young—that it becomes heedless of its own life and prefers to endanger itself rather than desert its eggs or its brood.

Therefore, there is no doubt that in this elementary lesson, God prohibited His people from savagery and cruelty.