Why does the Torah insert the words "Ve'amarta aleihem"?
Sifra: To incorporate Geirim and Avadim in the Din of Ma'arich.
What is the meaning of "Ish ki Yafli Neder"?
Rashi, Rashbam and Targum Yonasan: It means a man who expresses a Neder. 1
Temurah, 2b: "Ki Yafli" incorporates a 'Mufla ha'Samuch le'Ish' - a boy of twelve or of thirteen who has not yet grown two pubic hairs. 2
Why does the Torah insert the (otherwise superfluous) word "Ish ki Yafli Lindor Neder"?
Why does the Torah add a second 'Chaf'' in the word "be'Erk'cha"?
Rashi (in Pasuk 3): 'I do not know the reason for the extra 'Chaf''. 1
Rashbam (in Pasuk 3): The Torah sometimes doubles letters. 2
Sifsei Kohen: Because, from Hashem's perspective, the value of a Neshamah, which comes from under the Kisei ha'Kavod, is without limit. The Torah is therefore insinuating that "be'Erk'cha" - any fixed value is only from your perspective. 3
Erchin, 4b #1: It includes there where someone declares 'Erech Stam alai' without specifying, to teach us that he is Chayav to pay Hekdesh the smallest Erech (three Shekalim). 4
Erchin, 4b #2: It precludes where someone declares the Erech of a limb on which one's life does not depend 5 from the Din of Erchin. 6
Why does the Torah insert the (otherwise superfluous) word "b'Erkecha Nefashos"?
Rashi: To include a case where a person declares the Erech, not of a whole person, but of a major limb, without which the person cannot live.
Erchin, 4b #1: To incorporate where one declares the Erech of a limb on which one's life depends 1 in the Din of Erchin 2 - who must pay his full Erech.
Erchin, 4b #2: To preclude a dead person from the Din of Erchin. 3
Erchin, 4b #3: It implies that even if one person declares the Erech of a hundred people simultaneously, they all take effect.
Erchin, 5b: To incorporate women in the Din of Ma'arich.
Erchin, 20a: To incorporate someone who is disgusting and a leper in the Din of Ne'erachim. 4
If this Parshah was said at Har Sinai - as the Torah testifies in Pasuk 34, why did the Torah not insert it in B'har?
Ramban and Moshav Zekenim: Because, although some of the Pesukim are connected to the Yovel, 1 the Torah prefers to discuss all the Dinim of Neder together.
Seforno: Refer to 26:46:1:1*.
Ramban: Such as those that deal with the sanctification of fields that one purchases and that one inherits.
What are the connotations of "B'nei Yisrael" and of "Ish"?
Erchin 5b #1 (according to R. Meir): "Bnei Yisrael" teaches us that Yisrael can be Ma'arich 1 (pledge Erchin), but not Nochrim, 2 whereas "Ish" teaches us that even Nochrim 3 can be Ne'erach (assessed).
Erchin 5b #2 (according to R. Yehudah): "B'nei Yisrael" teaches us that Yisrael can be Ne'erach, but not Nochrim, whereas "Ish" teaches us that even Nochrim can be Ma'arich.
Rosh: This is a merit for Yisrael - in that through giving the value of their souls, Hashem will save them from the birth-pangs of Mashi'ach and Gehinom, about which the Navi writes in Yeshayah 30:33 "Aruch me'Esmol Tafteh" ('for hell has been prepared from yesterday'). And correspondingly, the Pasuk writes in Tehilim 23:5 - "Ta'aroch Lefanai Shulchan" ('And I will set a table in front of you').
Temurah, 3a: This also precludes Hekdesh animals belonging to Nochrim from making a Temurah.
See Torah Temimah, note 1.