To whom is "Makeh Re'ehu ba'Saser" referring?
Da'as Zekenim: The Gematriya of "Saser" equals that of 'Rechilus' (Chaser, without a 'Vav'). Ba'al ha'Turim
What is the significance of the twelve K'lalos?
Rashi (citing R. Moshe ha'Darshan): Eleven of the K'lalos 1 , correspond to all the tribes 2 except for Shimon - because, since Moshe did not intend to bless him 3 when he blessed the other tribes (in ve'Zos ha'Brachah), before he died, he did not curse corresponding to him. Refer to 33:6:5:1-3.
Rashbam (in Pasuk 15) and Targum Yonasan (in Pasuk 26): The twelve K'lalos correspond to the twelve tribes. 4
Refer to 27:24:151:1.
Gur Aryeh: Based on the fact that Moshe and Eliyahu did not ascend higher than ten [Tefachim], because above that pertains to the higher beings, eleven demonstrates that the K'lalos are from Hashem. 3. "Arur" begins with an 'Alef' (whose Gematriya is one), which alludes to an absence of increase; B'rachah begins with a 'Beis' (two), which signifies the beginning of increase.
Shem mi'Shmuel (5670): Since Moshe blessed the other tribes [in ve'Zos ha'Berachah, before the K'lalos were given], the K'lalos would not cleave to them. Hadar Zekenim - also Ya'akov did not bless Shimon. He did not bless Levi either - due to the episode with Shchem - but Levi did Teshuvah by the Eigel. R. Bachye explains that Moshe did not intend to bless Shimon due to the episode of Ba'al Pe'or.
Targum Yonasan (in Pasuk 26): These twelve covenants were made on Sinai, repeated in the Ohel Mo'ed and repeated again in the Plains of Mo'av
What is the word "Makeh Re'ehu" coming to preclude?
Ha'Kesav ve'ha'Kabalah: It precludes people who create feuds - to permit speaking Lashon ha'Ra about them. 1
The Yerushalmi in Pe'ah, 1:1 learns it from Adoniyahu (How can we learn it from Adoniyahu, who was considered a Rodef?) If he became king, he would have certainly tried to kill Shlomoh (Ralbag Melachim, 1 1:21)! Alei Tamar (Pe'ah 1:1) explains that every feud is prone to come to murder. Does this apply even to feuds over seats or honor in the Beis ha'Keneses? (PF. Indeed, a feud about who will be Shali'ach Tzibur once led to murder - Magihah to Chesed la'Alafim 53:7, citing Imros Kesef p.131).
QUESTIONS ON RASHI
Rashi writes that there are eleven K'lalos, But in fact, there are twelve?
Bartenura: Rashi does not count the last curse, since it pertains to the entire Torah, and not to any specific sin (Refer to 27:26:1:1).
