As we learned on yesterday’s daf there are two separate ways of committing to make a gift to the Temple based on a person’s value. Nidrei arakhin – the main discussion of the current tractate – is an established set of values for vows, which fluctuate depending on the age and gender of the person (see Vayikra 27:1-7). In contrast, nidrei damim refer to the worth of a person as determined based on how much that person would be sold for on the open slave market.
The Mishna on today’s daf points out yet another difference between the laws of nidrei arakhin and nidrei damim. If a person vows to donate the value of his forearm to the Temple, the Mishna teaches that we must establish the value of his forearm by evaluating how much he would be worth with or without the arm, and that must be paid to the Temple. The Mishna emphasizes that this is a case where the laws of arakhin differ. Were he to have said erekh yadi alai – i.e., had he made nidrei arakhin on his arm – no payment would be necessary at all. Arakhin are only meaningful if they relate to the entire person (or, minimally, to a part of the person without which he could not live, like his head or his heart).
How are we to determine the value of someone’s forearm for the purpose of nidrei damim?
Rava says simply that we evaluate the person in the slave market and determine the difference between his worth with or without his forearm. That difference is the value of the arm. Abaye argues that this type of valuation will not work in this case since the assessment of a man whose forearm is missing cannot be compared to establishing the worth of an arm of someone whose physical integrity remains intact. He therefore recommends that the valuation view him as a slave having both arms, the ownership of one being retained by the original owner.
Rashi explains that Abaye is concerned that the Temple will receive less than the true value of the arm, since the arm of a living, working slave will be seen as having greater value than that of a mutilated slave. Tosafot argue that it is the other way around. A lost arm affects the entire person, and therefore lowers his worth on the slave market more than the true value of the arm.