הלכה אויף ויקרא 24:20

Damage, in what manner? If he chopped off the hand or the foot of his fellow, we look at [the fellow] as if he was a slave being sold in the marketplace: how much was he worth [then] and how much is he worth now. And he pays the depreciation of his value that he caused. As it is stated, "An eye for (tachat) an eye" - from the tradition, they learned that that which it states, "for (tachat)" means to pay money.

That which it states in the Torah, "In the way that he gives a blemish to a man, so will it be given to him," is not [coming] to injure this one as he injured his fellow; but [rather] that it is fitting to remove a limb from him or to wound him as he did [to another]. And therefore, he must pay his damage. And behold, it states, "And you shall not take ransom for the soul of a murderer" - for a murderer only may you not take ransom, but for the loss of limbs or wounds, there is ransom.

And from where [do we know] that that which it states with regards to limbs, "An eye for an eye," is [to be understood as] payments? Since it is stated about it, "A wound for a wound," and it is explicitly stated, "And when a man strikes his neighbor with a stone or with a fist, etc... he should surely give him his rest and his rehabilitation." Behold, you have learned that "for (tachat)" mentioned with regards to a wound means payments. And this is [also] the case with "for (tachat)" mentioned concerning the eye and concerning the other limbs.