157. A Combination of Permitted and Prohibited Factors

Avodas Kochavim 7:13

We are not permitted to derive benefit from wood taken from an asheira tree. If a person heated his oven with such wood, he must cool it off, after which he lights it with permitted wood. After doing this, he may bake in the oven. If he bakes in the oven without cooling it first, he may not derive benefit from the bread. If the loaf baked in this latter example became mixed with other loaves, he must cast the value of the prohibited loaf into the Dead Sea so that he will not have benefit from it. The other loaves are permitted.

Avodas Kochavim 7:14

If a piece of wood from an asheira was built into a loom, one may not derive benefit from the garments it is used to make. If such a garment gets mixed with other garments, he must cast the value of the forbidden garment into the Dead Sea. The other garments are permitted.

One may plant vegetables under an asheira both in the summer - when they benefit from the shade - and in the winter. This leniency is because the vegetables' growth depends upon both the shade of the asheira, which is a prohibited factor, and the earth, which is a permitted factor. The general principle is that when a prohibited factor and a permitted factor combine, the result is permitted. Therefore, if a field was fertilized with manure used for idolatry, one may still plant in it. A cow that was fed beans used for idolatry may be eaten. The same is true in other such cases.