Related על דמאי 2:11

One takes upon himself four obligations that are placed on him to be a "chaver" (see Dem. 2:3): (1) he does not sell terumah or ma'aser to an am ha'aretz [a Jew who is not scrupulous in his observance, including the laws of purity and tithing], (2) he does not engage in cleanliness [?] at the home of an am ha'aretz, and (3) he [only] eats unconsecrated meat in a [state of] ritual cleanliness. [Note: per the GR"A, we add (4) he does not sell [Demai] to an am ha'aretz.]

These are the things that are sold in bulk: [all] types of grain. And beans are typically measured in small [quantities], the words of Rabbi Meir. But the Sages say, even things that are typically measured in small [quantities] and are [then] measured in large [quantities], these may be [measured] in abundance and sold as Demai [without first tithing]. [But] if they are measured in small [quantities], behold, these are liable [in the laws of Demai (and he must tithe them first)]. Rabbi Nehemiah says, [with regards to] the sale in small [quantities], behold it is like small [quantities], and in large [quantities], behold, it is like large [quantities] (i.e., all produce sold in bulk is treated the same, and all produce sold in small quantities is treated the same, without regard to what is "typical"). Rabbi Yishmael son of Rabbi Yochanan son of Berokah says, one who sells in small [quantities], behold, he is liable [to tithe] even if he sold [a quantity as small as] as a seah and a quarter (cf. Dem. 2:5), he needs to tithe the quarter (i.e. 20 percent of the whole, reflecting first and second tithes). Rabbi Shimon ben Gamliel says in the name of Rabbi Yosei, baskets of figs and baskets of grapes and bushels of vegetables (see Dem. 2:5) [sold for at at least ] a nummus ["לימין", a type of coin, see Jastrow] [are considered] a large quantity, and from a nummus and lower [is considered] a small quantity. And for moist [produce], a hin [and upward] [is considered] a large quantity and from a hin and lower [is considered] a small quantity. And so it happened that Rabbi Shimon ben Gamliel said in the name of Rabbi Yosei, [as to] a K'liyah (=triple-thread, per Jastrow) of garlic, behold, that is [considered] a large quantity. (Presumably, several heads of garlic were tied together and sold in this fashion.)

These are the things that are sold in bulk: [all] types of grain. And beans are typically measured in small [quantities], the words of Rabbi Meir. But the Sages say, even things that are typically measured in small [quantities] and are [then] measured in large [quantities], these may be [measured] in abundance and sold as Demai [without first tithing]. [But] if they are measured in small [quantities], behold, these are liable [in the laws of Demai (and he must tithe them first)]. Rabbi Nehemiah says, [with regards to] the sale in small [quantities], behold it is like small [quantities], and in large [quantities], behold, it is like large [quantities] (i.e., all produce sold in bulk is treated the same, and all produce sold in small quantities is treated the same, without regard to what is "typical"). Rabbi Yishmael son of Rabbi Yochanan son of Berokah says, one who sells in small [quantities], behold, he is liable [to tithe] even if he sold [a quantity as small as] as a seah and a quarter (cf. Dem. 2:5), he needs to tithe the quarter (i.e. 20 percent of the whole, reflecting first and second tithes). Rabbi Shimon ben Gamliel says in the name of Rabbi Yosei, baskets of figs and baskets of grapes and bushels of vegetables (see Dem. 2:5) [sold for at at least ] a nummus ["לימין", a type of coin, see Jastrow] [are considered] a large quantity, and from a nummus and lower [is considered] a small quantity. And for moist [produce], a hin [and upward] [is considered] a large quantity and from a hin and lower [is considered] a small quantity. And so it happened that Rabbi Shimon ben Gamliel said in the name of Rabbi Yosei, [as to] a K'liyah (=triple-thread, per Jastrow) of garlic, behold, that is [considered] a large quantity. (Presumably, several heads of garlic were tied together and sold in this fashion.)

They did not permit selling Demai except to a wholesale dealer (=סיטון, per Jastrow). A homeowner who sells both this and that (i.e., both large and small quantities, per Lieberman) needs to tithe, the words of Rabbi Meir. But the Sages say, one wholesale dealer and one homeowner are permitted to sell [Demai] and to send it to their friend, and give it to him as a present.