…A more complicated issue is whether a cigarette smoker could switch to vaping as a step towards cessation of all smoking, and on this authorities are still quite divided. There is rabbinic precedent that allows substitution of a less serious halachic violation for a more serious violation, i.e., that vaping, while harmful and generally forbidden, would be acceptable when replacing cigarette smoking, which is more dangerous. Authorities in this debate point to what other example where rabbis might allow a less serious transgression of Jewish law in lieu of a more serious one?