Related על דמאי 3:1

A chaver that was selling [produce] in abundance and [which] was tithed, and he was assigned something that was Demai, he needs to inform [the purchaser] because everything that is Demai, one needs to inform. Rabban Gamliel used to feed his workers Demai (see Dem. 3:1), and he let them know. But if a homeowner [has already] informed them about the same type [of produce (i.e., that he subsequently sells or provides them)], then he doesn't need to inform them [again].