The Mishnah on today’s daf (=page) continues with a discussion of differences between nidrei arakhin (an established set of values for vows, which fluctuate depending on the age and gender of the person – see Vayikra 27:1-7) and nidrei damim (the worth of a person as determined based on how much that person would be sold for on the open slave market) that we have been introduced to in the previous dapim.
If one said: I vow my valuation and then he dies, his heirs must pay it, but if he said: I vow my worth and then he dies, then his heirs need not pay anything because dead persons have no worth.
The contrast between these two cases stems from a question of timing and the need to determine the true value of the person about whom nidrei damim were taken. As we learned above (daf 18) in the case of nidrei arakhin we determine the value of the vow that was taken at the moment that the vow is taken. Therefore, the father who took this vow became obligated based on the Torah‘s payment schedule for someone of that age. Such a vow must be paid by the heirs even after their father passes away. With regard to nidrei damim, the value of the vow is determined only at the moment when the worth of the person is being established. At that time, the Mishnah teaches, the person has no worth and therefore the heirs are not obligated to pay their father’s vow.
The Shittah Mekubetzet and the Tosafot Yom Tov suggest that the reason the person has no worth after death is because according to Jewish law it is forbidden to derive benefit from a dead body. The Tiferet Yisrael argues that such an explanation is unnecessary, since there is a simpler reason why a dead body has no worth. Since we establish the worth of someone who takes a vow using the language of nidrei damim by taking him to the slave market to be evaluated, it is clear that a dead body has no value as a slave.