Genesis 9:5 - Joseph Benson’s Commentary on the Old and New Testaments

And surely your blood of your lives will I require The sense is, If I am thus careful of the blood of beasts, be assured I will be much more solicitous for the blood of men, when it shall be shed by unjust and violent hands. Our own lives are not so our own that we may quit them at our own pleasure; but they are God's, and we must resign them at his pleasure. If we any way hasten our own deaths, we are accountable to God for it. Yea, At the hand of every beast will I require it To show how tender God was of the life of man, he will have the beast put to death that kills a man. This was confirmed by the law of Moses, Exodus 21:28, and it would not be improper to observe it still. And at the hand of every man's brother will I require the life of man I will avenge the blood of the murdered upon the murderer. When God requires the life of a man at the hand of him that took it away unjustly, as he cannot render that, therefore he must render his own in lieu of it, which is the only way he hath of making restitution.