How concerned must someone be about damage that is caused indirectly by his property?
The Mishna on today’s daf teaches that a person should not plant trees next to his neighbor’s field unless he leaves four amot of empty space. According to the Mishna, this applies to both ordinary trees and to grape vines. In the Gemara, Shmuel teaches that the need for four amot is only in Israel; in Bavel only two amot was necessary. Rashi explains that this is a technical issue – that in Bavel a narrower plow was used. Others suggest that since the ground in Israel was harder to work, it was common to use oxen, which took up more space than the donkeys that were popularly used in the softer Babylonian soil.
The Gemara tells the following story:
Rava bar Rav Ḥanan had palm trees in his field near Rav Yosef’s vineyard. Birds that flocked to Rava bar Rav Ḥanan’s trees would damage Rav Yosef’s fruit, and Rav Yosef demanded that Rava cut down his trees. Rava insisted that he had planted his trees reasonably distant from Rav Yosef’s field and therefore had no obligation to cut down his trees. Rav Yosef countered that there needed to be a larger amount of space left between trees and grapevines. Finally Rava refused to cut down his trees on the grounds that they produced a significant amount of fruit and that Rav taught that a tree that produced a kav of fruit could not be cut down because of bal tashḥit, the prohibition against wasting or destroying food (see 20:19). He concluded by telling Rav Yosef that if he felt that the trees had to be cut down, he would have to do it himself.
The question raised by many of the commentaries is that if Rava’s trees were truly causing damage to Rav Yosef, surely he was obligated to cut them down. The Rashba suggests that even Rav Yosef did not claim that the damage was directly caused by Rava’s trees, and that he was not obligated to cut down the trees, rather that it would be a pious response. Rava countered that since he wasn’t truly obligated, there were other concerns that kept him from cutting them down.