Êxodo 21:24 Midrash: Mekhilta DeRabbi Yishmael, Ein Yaakov (Glick Edition), Mekhilta DeRabbi Shimon Ben Yochai & Sifrei Devarim

(Exodus 21:15) "And if one strikes his father and his mother, he shall be put to death": What is the intent of this? Because it is written (Leviticus 24:20) "an eye for an eye, etc.", and Scripture took it (striking father or mother) out of its category to make it more stringent, to make it liable to the death penalty, this section was, therefore, stated.

(Exodus 21:18) "And if men quarrel": What is the intent of this section? It is written (Ibid. 21:24) "an eye for an eye," but sheveth (work-disability payment) and ripui (medical expenses) are not mentioned. It is, therefore, written (Ibid. 19) "If he arise, etc." Scripture comes to teach of (other payments) that are due him.

"an eye for an eye" money. You say "money," but perhaps an eye (literally) is intended? R. Elazar was wont to say (Leviticus 24:21) "One who strikes a beast shall pay for it, and one who strikes a man shall be put to death." Scripture likens the injuries of a man to the injuries of a beast, and the injuries of a beast to the injuries of a man. And just as the injuries of a beast are subject to monetary payment, so, the injuries of a man.