Nedarim (62b) Rava said: It is permitted for a Torah scholar to say: I will not pay the head tax [karga], as it is written that the king of Persia wrote to Ezra, with regard to the priests, the Levites, and others who worked in the Temple: “It shall not be lawful to impose minda, belo, and halakh upon them” (Ezra 7:24). And Rabbi Yehuda said: Minda; this is the king’s portion. Belo; this is the money of the head tax. And halakh; this is arnona, a levy on people and their animals to perform physical labor in the service of the ruling authority. Since a Torah scholar is considered equivalent to a priest, as he is also dedicated to a sacred task, this exemption applies to him as well.
And Rava said further: It is permitted for a Torah scholar to say: I am a servant of the priests of fire worship and therefore I will not pay the head tax. Rava maintains that a scholar may issue a statement of this kind in a place where the priests of fire-worshippers are exempt from the head tax, because he actually is declaring himself a servant of God, who is referred to as “a devouring fire” (Deuteronomy 4:24). What is the reason that he is allowed to make this statement? He is saying it merely in order to chase a lion away from him, i.e., to avoid suffering a loss.
The Gemara relates that Rav Ashi had a particular forest, and he sold it for its wood to the temple of fire worship. Ravina said to Rav Ashi: Isn’t there the prohibition: “You shall not put a stumbling block before the blind” (Leviticus 19:14), which prohibits assisting others in committing transgressions? And yet you are providing assistance to an idolatrous cult. He said to him: Most of the wood they use is for kindling, not for their ritual service. Consequently, I need not be concerned that the particular wood that I have sold them will be used for idolatry.
