Shabbat, Chapter Sixteen, Mishnah Five
This mishnah introduces means which may be used to keep the fire from spreading.
1) Rabbi Shimon ben Nannas says: one may spread a goat skin over a box, chest, or trunk which has caught fire, because he singes.
2) And one may make a barrier with all vessels, whether full [of water] or empty, that the fire should not travel onward.
a) Rabbi Yose forbids in the case of new earthen vessels filled with water, because since they cannot stand the heat, they will burst and extinguish the fire.
Section one: Rabbi Shimon ben Nannas allows one to spread a goats hide over various types of boxes since the hide wont burn but will only become singed. The will serve as an effective barrier from the fire.
Section two: Other barriers may also be erected, and one may fill vessels even with water to prevent the fire from traveling onward. Even though this will almost surely cause the fire to go out, since the fire is being put out indirectly it is permitted in a case such as this where there is a fear of financial loss.
Rabbi Yose, however, prohibits setting up new vessels filled with water to stop the fire since these will certainly break. Rabbi Yose holds that it is forbidden to indirectly cause a fire to be extinguished, even if this will cause a loss.