Reference for Exodus 21:30

In case an ox gores a man and kills him, it is possible that the animal is known to be dangerous and that its owner has been warned and would therefore have to forfeit his life together with the beast. Nevertheless the Bible offers the owner of the animal an opportunity to redeem himself by the payment of a sum of money. (Exodus, 21:30.) Of such a case Rabbi Ishmael said: “Here we may see the great mercy of the Creator who permits a man to redeem himself with money from a well-earned punishment.”