משנה על עבודה זרה 5:1

From when may one buy luf after the seventh year? Rabbi Judah says: immediately. But the sages say: [only] after the new crop has appeared.

These are the implements which a craftsman may not sell in the seventh year:A plow and all its [accompanying] implements, a yoke, a winnowing-fan, and a pickax. But he may sell a sickle used by hand, a scythe, and a cart with all its implements. This is the general principle: any tools designed for work involving a transgression [in the seventh year] is prohibited; but if for a forbidden and a permissible purpose, it may be [sold].

If the wife of a haver left the wife of an am haaretz grinding grain in her house, if the handmill stopped turning, the house is unclean. But if the handmill did not stop turning, that part of the house which she can stretch out her hand and touch is unclean. If there were two women, the house is unclean in either case, since while the one is grinding, the other can go about touching, the words of Meir. But the sages say: the only part that is unclean is where she can stretch out her hand and touch it.