The Torah says: "You shall not burn fire in all your dwellings on the day of Shabbat." The Mishnah of Tractate Shabbat, in the context of laws prohibiting cooking, states: "One who heats a metal pot may not pour cold water into it to heat [the water], but he may pour water into the pot or a cup in order to temper [the vessel]."[8] In the Gemara, Rav says it is permitted to add water to cool it, but forbidden to add water to mold the metal. Shmuel says it is also permitted to add enough water to mold the metal as long as that is not his intent, but if he intends to mold the metal it is forbidden. In a different context, Rav Sheshet says that "cooking" a metal filament is forbidden by analogy to cooking spices.
Thus, heating a metal filament might violate cooking, igniting a fire, or both. Rambam classifies heating metal as a subcategory of igniting a fire, but only if the intent is for metalwork.[11] Raavad disagrees with the first category but does classify it as cooking or as completing a product (Hebrew: מכה בפטיש, makkeh bapatish: literally, "striking the final hammer blow"). The majority of later authorities accept that heating a metal filament is forbidden as igniting a fire, and also agree that turning on an incandescent light bulb falls within the definition of this prohibition.

Nobel Prize-winning physicist Richard Feynman recounts that he was approached by young rabbis in a seminary who asked him "is electricity fire?". He replied, "no", but asked why they wanted to know, and was shocked that they weren't interested in science at all, but just wanted to interpret the Talmud. Feynman said that electricity was not a chemical process, as fire is, and pointed out that there is electricity in atoms and thus every phenomenon that occurs in the world. Feynman proposed a simple way to eliminate the spark: '"If that's what's bothering you, you can put a condenser across the switch, so the electricity will go on and off without any spark whatsoever—anywhere.' But for some reason, they didn't like that idea either"

Rutstein was a principal founder of Yeshiva Chaim Berlin and was critical in establishing Chaim Berlin Yeshiva in the United States. An article in the Brooklyn Eagle, on March 16, 1942, describes one of the many donations he acquired for the institution, stating that "$2,000 was raised in outside gifts by Jacob Rutstein who recently returned from Florida." On December 11, 1944, another article appears in the Brooklyn Eagle which it states that, "Yesivah Rabbi Chaim Berlin, one of the largest Orthodox Jewish institutions of learning in the country, is dedicating its new seven-story building at Stone and Pitkin Ave. at ceremonies which will take place throughout the week. The opening ceremonies were attended by more than 3000 persons. Jacob Rutstein, chairman of the dedication committee, announced that $25,000 had been donated by those present towards the new $1,000,000 building."
On December 29, 1944, another article appeared stating the following about Rutstein:
"Our congratulations to Jacob Rutstein for his constant activity on organizing activities for the advancement of orthodox Jewish secular and religious education. Outstanding in his philanthropic activities is his recent purchase of the seven-story $1,000,000 building at 350 Stone Ave. for the Mesivtah and Yeshivah Rabbi Chaim Berlin in the hearts of Brownsville. Already the institution has been recognized by the State Board of Regents through the granting of a charter and 800 students are now enrolled. Of this number 150 are studying for the rabbinate. Also 200 of its students have come from all parts of this country and 62 are refugees driven from their homelands by Hitler. This has been a truly humanitarian endeavor on the part of Mr. Rutstein."

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