Perek 12

Ramban comments on the strange phrase והאיש משה ענו מאד. 

He says that the Torah adds this detail about Moshe because it explains why Hashem had to defend him. Moshe was too humble to stick up for himself. 

Ramban then quotes the opinion of Rav Eliezer which says the same thing. That Moshe would never ask anything of anyone or do anything and that he wouldn't go against anyone. 

Lastly, he quotes an opinion which is different than his own, the Sifri. It says that the Torah uses this phrase to describe Moshe because he was standing with his siblings when they spoke about him and he was humble in that he controlled himself and didn't respond. Then Hashem responded for him. 

Perek 10

כט  וַיֹּאמֶר מֹשֶׁה, לְחֹבָב בֶּן-רְעוּאֵל הַמִּדְיָנִי חֹתֵן מֹשֶׁה, נֹסְעִים אֲנַחְנוּ אֶל-הַמָּקוֹם אֲשֶׁר אָמַר יְהוָה, אֹתוֹ אֶתֵּן לָכֶם; לְכָה אִתָּנוּ  וְהֵטַבְנוּ לָךְ, כִּי-יְהוָה דִּבֶּר-טוֹב עַל-יִשְׂרָאֵל

Who is Chovev ben Reuel, the father-in-law of Moshe? Is it Yitro? If so why the new name?

Chovev is in fact Yitro and he has a new name because after he accepted Torah he was given a new name, which was the practice among converts.

Yitro originally thought that when Moshe said "Viheitavnu Lach" Yitro thought they would give him of the spoils of the war to conquer Israel but they would not give him a Nachala, so Yitro declined because in his homeland he had a portion.

But Moshe impresses on him how Bnei Yisroel need him to be their eyes in the desert and be a guide for them on their way up to Eretz Yisroel. And Moshe makes sure this time to tell Yitro that he will be given a Nachala in the land, which will be a reward for his help.

The Gemara in Bechorim tells that Yitro did go with Bnei Yisroel and sites the above passuk as the proof.

Perek 5

יח): וביד הכהן יהיו מי המרים המאררים)

Question- Is the water bitter?

"Imru hamipharshim"- Ramban quotes others who base their translation on the outcome. The water is going to be bitter for the woman because they will bring her sin into the light.

He then quotes two sources, the Gemara in Sota and the Sifri, which say that the water being "Mar" is not based on the outcome, rather the Cohen puts something in the water to make it bitter. Ramban adds that if this were true then in pasuk 27 it shouldn't say  "ובאו בה המים המאררים למרים" (that the cursed water became bitter) rather it should say  "ובאו בה המים המרים למאררים" (that the bitter water became a curse). 

"Hanachon Bi-eini"- the water that she drinks is sweet like normal water. When she is brought close then the the woman will be "Miarer" and the water will turn bitter (just like pasuk 27 says). And the word "Miarrim " is used because of the possibility that the water will curse her.

"Viimru Hamipharshim"- Ramban as an aside quotes a machloket as to what is the key aspect of the "Mei Marim". Either it is "Marim" next to "Mayim" or "Mei" next to "Marim". Ramban sides with "Marim" next to water because of what is says later on when it is "Mayim Hamiarrim" that turns to "Marim".

This Ramban is reflective of his regular style. He quotes other opinions that he doesn't agree with, the "Imru hamipharshim". Then he quotes sources that could help lead to an answer, but here there is no consensus. Then he gives his opinion, the "Hanachon Bi-eini". Lastly he clears up another issue in the text that wasn't directly related to his original question but that arose from the passuk.

Biography

Name: Ramban (Nahmanides)

Date of Birth: 1194 CE

Hometown: Girona, Catalonia in the kingdom Aragon, Spain

Predominant Philosophy: Kabalah

Interests: law, medicine, mysticism

Work: Perush al HaTorah, Chidushei HaRamban, Milchamot Hashem, Mishpatei HaCherem, Hilchot Biddikah, Torat HaAdam

Professional Career: Chief Rabbi of Catalonia

Claim to Fame: His participation in the Disputation of 1263. He was invited by King James to participate in a debate with the Christian convert Pablo Christiani. Hebattled heroically, and he subsequently published his arguments in the book Sefer HaVikuakh. But do to his success the Dominicans in Spain launched a campaign to prosecute Ramban.

Travel:  Jerusalem, Israel

Interesting Fact: Ramban was nine years old when Rambam (Maimonides) died. A lot of Ramban’s work came in the face of the Maimonidean controversy in Ashkenazi lands.

Death: 1270 in Jerusalem

Source: http://www.jtsa.edu/Conservative_Judaism/Ramban_Biography.xml          

             http://en.wikipedia.org/wiki/Nahmanides#Works