Why did Reuven refer to "this pit that is in the desert"?
Ramban, Malbim: The pit was very deep, so Yosef would not be able to escape, 1 and it was in a location where nobody was likely to hear his screams. Ha'amek Davar - Also, it was far from where the brothers were staying, so Reuven would be able to return Yosef to Yaakov without their knowledge.
Hadar Zekenim: He wanted them to cast Yosef into a pit that did not contain snakes and scorpions. However, they ignored his request. 2
Oznayim la'Torah: The brothers said to throw Yosef into one of the local pits, because it made no difference to them into what sort of pit they threw him. 3 Reuven however, who intended to come back and save him, pointed to a specific pit which (a) did not contain snakes and scorpions, and (b) which he would later be able to identify.
Moshav Zekenim rejects Rashi who says in Bava Kama 50b, that a Stam Bor in the Torah is 10 Tefachim deep; because if so, Yosef could have easily escaped!
Riva concludes unlike this, for "ha'Borah" connotes the pit discussed until now.
Moreover, the words "Lechu v'Nahargehu, v'Nashlichehu b'Achad ha'Boros" implies that they should kill him and throw his corpse into one of the local pits.
What prompted Reuven to save Yosef's life and to even attempt to return him to his father?
Rashi: His sense of responsibility in his capacity as the Bechor, 1 because he realized that the blame would fall on him.
Bereishis Rabah 84:15: Reuven thought that he was expelled from Klal Yisrael due to the episode with Bilhah. However, when Yosef related his dream and counted him with the brothers, he reassured him that this was not the case. And it is due to Hakaras ha'Tov that he tried to save him. 2
Oznayim la'Torah: Considering that the brothers' hatred was based on the fact that Yosef wanted to rule over them - by taking the kingship and the Bechorah, one would have expected Reuven, who, at that stage, was heir to the throne and the Bechorah, to be the first to call for his death. The fact that it was specifically Reuven who saved him demonstrates an incredible display of good Midos. 3
Ha'amek Davar: We should not punish him for his words and dreams - this is mere childishness! This is why he said "ha'Yeled Einenu," "Al Techet'u va'Yeled" (37:30, 42:22). However, they did not accept this.
Even though he seems to have somehow known that he would lose the birthright to Yosef. Refer to 29:32:151:1.
Mishnas R. Aharon Vol. 3, p. 111-112: Reuven was the Bechor. He should have been the most upset that Yosef tells his dream! Rather, his spirit was very low due to Teshuvah, therefore he understood unlike his brothers. Hearing that they will bow to Yosef caused Reuven to love him, and caused the others to envy him.
How did Reuven convince his brothers to fall in line with his suggestion?
Ramban: By suggesting that they do not kill him directly. He said "Dam," and not Damo, to teach that they should not kill anyone directly; [and implied that] he does not say so amidst compassion for Yosef. 1
Refer to 37:21:1:3.
Seforno: He said that they should not kill him in a cruel manner (rather, let him die automatically 2 in the pit).
Malbim: One must be more careful about something explicit in the Torah - "Shofech Dam ha'Adam" (9:6). 3
Ramban: As a matter of fact, initially, it was only after they rejected his initial proposal to leave him alone altogether, that he suggested throwing him into the pit. See Bereishis 42:22.
Gur Aryeh: See 37:22:3.1:1.
Malbim: This is why Chachamim enacted not to excommunicate an Av Beis Din who soured (Moed Katan 17a), for it says "v'Nasi b'Amcha Lo Sa'or" (Shemos 22:27).
Why does the Torah make a point of mentioning "Lema'an Hatzil Oso mi'Yadam... "?
Teshuvas ha'Rashba (Siman 981): To teach us that one should record and publicize someone who performs a Mitzvah.
QUESTIONS ON RASHI
Rashi writes: "'In order to save him' - [The Torah] is testifying about Reuven, that he said this only in order to save Yosef." How else might I have explained the Pasuk?
Gur Aryeh: One might have explained that Hashem caused Reuven to say this, in order that Yosef be saved (despite that Reuven himself might have had other intentions in mind). Rashi therefore explains that Reuven himself was trying to save Yosef. 1
Gur Aryeh: We can prove this from the verse's conclusion, "... to return him to his father." That was in fact Reuven's intent, to return Yosef home. Whereas Hashem's plan was to save Yosef from death, and not return him home (but rather, to bring Yaakov and his family down to Yosef, in Mitzrayim).
Rashi writes: "[The Torah] is testifying... that he said this only in order to save Yosef." But Rashi (to 37:24) writes that there were snakes and scorpions in the pit! (The Gemara (Yevamos 121a) says that one who fell into such a pit is presumed dead, and his wife may remarry!) How is this called saving Yosef?
Ramban: The pit was too dark or too deep, or the snakes were hiding in the crevices. Reuven was not aware that there were snakes and scorpions, because he could not see them. 1
Moshav Zekenim #1: The pit was wide, so Yosef would not necessarily have fallen on the snakes, and they would not necessarily have killed him.
Hadar Zekenim, Moshav Zekenim #2: Reuven wanted them to cast Yosef into a specific pit that did not contain snakes and scorpions. However, they ignored his request.
Gur Aryeh: To be more precise, the Gemara (Yevamos 121a-121b) says a pit that is full of snakes and scorpions can be presumed lethal. Yosef's pit was not full, it had some snakes and scorpions, and perhaps Yosef would manage to kill them before they could harm him. 2
Ramban: Had they known, they would have realized, when Yosef emerged alive from the pit, that he was a great Tzadik, and they would never have gone on to sell him into slavery (compare to Daniel 6:23). In any event, based on their decision not to kill him directly, they would not have thrown him into a pit with snakes and scorpions (refer to 37:24:2:2; and 37:21:151:1).
Riva: Or charm them.
Rashi writes: "[The Torah] is testifying... that he said this only in order to save Yosef." Reuven told his brothers not to kill Yosef outright, but rather to throw him in the pit. Yet it seems the brothers still presumed that Yosef would die there! As Yehudah later says, "What do we gain by killing our brother" (37:26)?
Gur Aryeh: Reuven was able to convince the brothers not to kill Yosef directly, but rather indirectly, by throwing him into a pit without food or water. Such an act is not punishable as murder by Beis Din. (Reuven then planned to raise Yosef out of the pit at the first opportunity.) Yehudah later argued that they should not even cause Yosef's death indirectly, but rather to sell him as a slave.
