897. The Fire for Havdalah
Shabbos 29:25
A bracha is not recited over the fire until we have benefited from its light sufficiently that one could differentiate between the coins of different nations. One may not recite the bracha over a fire belonging to non-Jews because it may have been used at a gathering for idolatrous purposes. We may likewise not recite the bracha on a fire that was lit for the worship of idols or for the sake of a deceased person.
Shabbos 29:26
If a Jew lights a fire from a non-Jew’s flame, or vice versa, we may recite a bracha over it but if one non-Jew lit a fire from another non-Jew’s flame, a bracha may not be recited over it. If one is walking outside a large city and he sees a light, then if most of the city's residents are non-Jews, he may not recite the bracha over it, but if most of the residents are Jewish, he may. Optimally, one should not recite this bracha over the fire of a furnace, an oven or a stove. If coals are glowing so much that a sliver of wood would catch fire on their own, the bracha may be recited over them. The bracha may be recited over the light of the study hall if there is an important person there for whom the light is lit. We may recite the bracha over the light of a synagogue if there is an attendant who lives on the premises. The optimum way to perform the mitzvah is to use a torch for havdalah. There is no need to go looking for fire the way one normally seeks to fulfill mitzvos. Rather, if one happens to have a flame, he should recite the bracha over it.