In the midst of the discussion of the responsibilities that a person who sets a fire will have for any damage that was caused, the Gemara shares a series of aggadic traditions that touch on this issue. One example is an examination of the passage in II Shmu’el (23:15-16) in which King David appears to be asking for water brought from Bet Lehem, leading three of his fighters to break in to the Philistine camp to get the water for him. The Gemara apparently rejects the simple meaning of this pasuk, preferring to understand it as containing a deeper meaning. The “water” of Bet Lehem represents Torah, indicating that King David had a Torah issue that he needed to clarify.
Several suggestions are put forward by the Sages. Rav Huna suggests that the Philistines were hiding among the Jewish barley fields and King David was unsure whether he was allowed to burn them down in order to save himself from his enemies. Is it permissible for a person to save himself with someone else’s money? In response his colleagues ruled that it was not permissible, but as monarch he had the right to take away – or destroy – property belonging to his subjects.
Rashi understands the question as presented, that King David was unsure whether he could destroy the field to save himself. According to Tosafot, we take for granted that a person can do so; the question at hand is whether he is obligated to pay for what he destroyed, or, perhaps, since it was done to save a life, there is no obligation to pay. The Ra’avad discusses this question at length, concluding that a person can certainly save himself at the expense of destroying another person’s property. If, however, the issue was someone saving his fortune at the expense of destroying his friend’s property (that is worth less than his) it would be forbidden to do so without permission from that person.