Reference for Leviticus 24:29

The Great Synagogue also appointed judges in all places where Jews resided so that everyone could find justice according to the laws of the Torah. They determined the content of “Tefillin” and “Mezuzoth” on the door posts and tightened all prohibitions, even forbidding many things which were previously permitted. This was done to prevent laxity in the observance of all prohibitions. The commandment of the Torah “an eye for an eye” they interpreted to mean that monetary compensation should be granted to the victim for the damage caused him instead of the literal meaning which is implied in Leviticus 24, 2.