One who accepts upon himself to be trustworthy (ne’eman), must tithe whatever he eats and whatever he sells and whatever he buys, and he may not be the guest of an am haaretz. Rabbi Judah says: even one who is the guest of an am haaretz can still be considered trustworthy. They said to him: He is not trustworthy in respect of himself! How can he be considered trustworthy in respect of others?

One who takes upon himself to become a “chaver” may not sell to an am haaretz either moist or dry [produce], nor may he buy from him moist [produce], nor may he be the guest of an am haaretz, nor may he host an am haaretz as a guest while [the am haaretz] is wearing his own garment. Rabbi Judah says: he may not also raise small animals, nor may make a lot of vows or merriment, nor may he defile himself by contact with the dead. Rather he should be an attendant at the house of study. They said to him: these [requirements] do not come within the general rule [of being a chaver].

Bakers the sages did not obligate them to separate [from demai produce] any more than suffices for terumat maaser and for hallah. Grocers may not sell demai [produce]. All [merchants] who supply in large quantities may sell demai. Who are those who supply in large quantities? Those such as wholesalers and grain-sellers.

Rabbi Meir says: [if produce] which is usually measured out [for sale] in a large [quantity] was measured out in a small [quantity], the small quantity is treated as if it was a large [quantity]. If [produce] which is usually measured out for sale in a small [quantity] was measured out in a large [quantity], the large [quantity] is treated as if it was a small [quantity]. What is considered a large quantity? For dry [produce] three kavs, and for liquids, the value of one dinar. Rabbi Yose says: baskets of figs, baskets of grapes, and bushels of vegetables when he sells them in lumps, they are exempt [from the rules of demai].