Why does the Torah insert the (otherwise superfluous) word "ve'Ish ki Yiten Mum ba'Amiso"?
Baava Kama, 27a: To extrapolate "Ish ba'Amiso", 've'Lo Shor ba'Amiso' - to exempt the owner of an ox that wounded somebody from paying the five things. 1
Since we would otherwise learn Shor - which is Chayav Kofer, via a Kal va'Chomer, from Adam - who is not.
Why does the Torah insert the (otherwise superfluous) words "Ka'asher Asah"?
Sifra #1: To include all forms of d See Torah Temimah, note 55.amage - even if they are not actually blemishes, such as splitting a person's ear, pulling out his hair, spitting on him, removing his clothes or uncovering a woman's hair in the street. 1
Sifra #2: To include where one takes hold of someone and holds him in the sun until he burns or in the cold and he freezes and where he incites a dog or a snake to bite him - all of which fall under the category of 'Garmi' (direct cause of damage) and are Chayav.
See Torah Temimah, note 52.
What kind of blemish is the Torah discussing?
Moshav Zekenim citing the Sifra: We learn from a K'lal u'Ferat u'Chelal - The current Pasuk is a Klal. "Ayin Tachas Ayin", a Prat and "Ka'asher Yiten Mum", a Klal - that just as the P'rat is a permanent blemish in an external, exposed limb (so one is liable for all smilar wounds). Similarly, an Eved Cana'ani goes free (if his master knocked out such a limb). 1
Moshav Zekenim: If so, if the master struck his slave's hand and it will recover, just like he does not go free, we should say that one does not pay Sheves Gedolah (decrease in what one would pay to buy such a person for a sLave, based on his lifelong loss of earning potential). Abaye says that he pays Sheves Gedolah and Ketanah (compensation for inability to do even work that does not require his hand at all, until he recovers! He could also ask about other limbs that do not set a slave free, e.g. he broke his arm. - PF)
