[Regarding] bakers, the Sages required them to separate only [a quantity] sufficient for terumas maaser and challah. Shopkeepers are not permitted to sell demai. All who sell with a large measure are permitted to sell demai. These are those who sell with a large measure: [those] such as grain wholesalers and sellers of grain.

One who accepts upon himself to be a chaver does not sell to an am haaretz wet or dry [food], does not buy from him wet [food], is not hosted by an am haaretz, and does not host him in his clothes. R’ Yehudah says: Also, he should not raise small domesticated animals, he should not overindulge in vows and frivolity, he should not render himself tamei [through contact] with dead bodies, and he should serve in the House of Study. They said to him: These things are not included.