We may go out with a locust’s egg, or with a fox’s tooth, or with a nail from a gallows, for the purpose of healing — [these are] the words of R’ Meir. But the Sages say: Even on weekdays these are forbidden because of [the prohibition against following in] the ways of the Emorites.

A major rule was stated [by the Sages] concerning the Sabbath: Anyone who forgot the essence of the Sabbath, and performed many labors on many Sabbaths, is liable for but one sin offering; one who knew the essence of the Sabbath, and performed many labors on many Sabbaths, is liable for every Sabbath; one who knew that it is the Sabbath, and performed many labors on many Sabbaths, is liable for every primary [category of] labor; one who [knew that it is the Sabbath, and] performed many labors of one [category of] labor, is liable for but one sin offering.