(Mishnah): If a person was eating a bunch of grapes and he entered from the garden into the courtyard (thereby obligating the grapes in Terumos and Ma'asros) - R. Eliezer says that he may finish eating it in the garden; R. Yehoshua says that he may not finish it (without tithing).

If night fell on Friday night - R. Eliezer says that he may finish eating it; R. Yehoshua says that he may not. (Unlike on a weekday, on Shabbos, one may not even snack on untithed produce, but one may also not tithe on Shabbos.)

(Gemara) (Mishnah in Maseches Ma'asros): If a vine was planted in a courtyard that creates an obligation to tithe, according to R. Tarfon, he may eat from it a cluster (without tithing). The same is true for a whole pomegranate or a whole melon. (R. Akiva disagrees and permits eating only single grapes.)

(R. Zeira/ R. Chiya citing R. Yochanan): R. Tarfon reasons like R. Eliezer (of our Mishnah)...

R. Tarfon viewed detaching the food from its stem as the beginning of eating the entire cluster.

(R. Ila/ R. Yasa citing R. Yochanan): R. Tarfon reasons like R. Eliezer...

R. Tarfon says that even if he takes a fruit that has in it two or three 'eatings', it's considered one eating.

What's R. Eliezer's reasoning? Since he began with permission.

Baraisa (R. Nasan): It's not that R. Eliezer said that it's because he began with permission; rather, R. Eliezer says that he should wait until Motzei Shabbos or until he goes outside the courtyard.

If Terumah wine, and certainly Chulin wine, was left uncovered, he must spill it out (since there is a danger that a snake left his venom in it). Three drinks become prohibited if left uncovered - water, wine and milk. All other drinks are permitted. How long must they be uncovered to become prohibited? Enough time for the snake to come out from a nearby place and drink from it.

The quantity of water that remained uncovered that would nevertheless be permitted is enough to nullify the poison in it.

(R. Yosi): For vessels, any quantity is still prohibited. For a hole in the ground, until 40 Se'ah (is prohibited).

Figs, grapes, cucumbers, pumpkins, melons or sweet melons that are bitten, even if they are large (and a person might think that they can eat from the area which is far from the hole), whether they are detached or still attached to the ground, as long as they are still moist, they are prohibited. And if it's been bitten by a snake, it is prohibited because there would be a danger to life for one who eats it.

A wine filter is prohibited because it's considered uncovered. R. Nechemia prohibits it.

(Gemara) (R. Yaakov bar Acha/ R. Shimon bar Ba citing R. Chanina): Wine that was left uncovered must be spilled, even if it is Terumah. A pot of food that was cooked with water that had been left uncovered must be spilled, even if it is Terumah.

(R. Yosi): Our Mishnah teaches this - If Terumah wine, and certainly Chulin wine, was left uncovered, he must spill it out.

(Chevraya citing R. Yochanan): If wine was left uncovered, one may not leave it (without spilling it away). If he left it and it fermented into vinegar, it is still prohibited. Figs and grapes that were bitten may not be left and if he left them and they naturally dried out (into dried figs or raisins), they are permitted.

The daughter of R. Chiya the Great would bite figs so that others wouldn't eat from them. Her father would eat from them.

Question: Isn't that prohibited?

Answer: He knew that his daughter did this.

Question: Nevertheless, it should be prohibited! Doesn't the Tosefta teach that if one saw a bird nibbling from a fig or a mouse nibbling from a melon, it is prohibited, as we are concerned that they were eating from the area that a snake had previously eaten...?

Answer: His daughter was careful to ensure that a snake hadn't eaten there previously.

(R. Yitzchak bar Nachman citing R. Yehoshua ben Levi): Sharp, bitter and sweet wines are no problem to leave unattended. (A snake wouldn't drink from them.)

(R. Simon citing R. Yehoshua ben Levi): Sharp, bitter and sweet wines are not prohibited if left unattended, nor are they prohibited as Yayin Nesech (as an idolater wouldn't use them for idolatry).

(R. Simon explains): Sharp refers to Kunditun (wine mixed with spices). Bitter is Pastinun (wine together with a bitter herb called Pastinun). Sweet is wine that was cooked until it becomes sweet.

R. Yehoshua bar Zidal had cooked wine that had been left in the possession of a gentile. He asked R. Yannai son of R. Yishmael as to its status. R. Yannai answered, "Didn't R. Shimon ben Lakish says that sweet wine has no prohibition if left unattended; nor does it become prohibited as Yayin Nesech?!''