What is the meaning of "Ki Yad al Keis Kah ... "?
Rashi, Ramban #1 (citing Midrash Tanchuma), Targum Onkelos and Targum Yonasan: It means that Hashem's Hand is raised to swear by His Throne, that He will personally continue to fight Amalek and to treat him like an enemy forever.
Ramban #2 (citing R. Yeshu'a, cited in the Ibn Ezra) 1 : The battle against Amalek will take effect when there will be a king 2 (Sha'ul) sitting on the throne of Hashem. 3
Ramban #3 (According to Kabalah): "The Hand which is on the Throne of Hashem" refers to the Midas ha'Din shel Ma'alah, which denotes Hashem's battle against Amalek in all generations. 4
Seforno: The reason that Moshe Davened to Hashem to be his champion 5 was because Hashem swore to fight Amalek from generation to generation, and Yisrael are obligated to fight His battles in every generation.
Rashbam: Moshe is explaining why he called the name of the Mizbe'ach 'Hashem Nisi' - Refer to 17:15:2:3 - because it is the way to call a person or an object after the miracle that occurred. 6
Sanhedrin, 20b: The sequence in the Pasuk teaches us that the Mitzvah of appointing a king 7 comes before that of fighting Amalek. 8
Mechilta: As soon as Hashem sits on His Throne, He will make battle with Amalek.
Sifri (in Ki Seitzei): From here we learn that Hashem swore 9 by His Throne of Glory that not leave over anything that belongs to Amalek under the Heaven.
See Rashbam's objection to this explanation.
Since "Keis Kah (Kisei) Hashem" is synonymous with the king of Yisrael. See Divrei ha'Yamim 1, 29:23 (Ramban).
The Gemara states in Sanhedrin, 20b that 'Yisrael were commanded three Mitzvos upon entering Eretz Yisrael - to appoint a king, to wipe out Amalek and to build the Beis-ha'Mikdash (Seforno). See also Torah Temimah, note 16.
Rashbam: Like we fin 'Eliezer' - in Yisro Sh'mos, 18:4, 'Imanu Keil' - in Yeshayah, 7:14 (and "Keil Beis-Eil - in Vayishlach Bereishis, 33:20:1:1**).
Sanhedrin (Ibid.): Since Kisei is synonymous with Malchus, as the Pasuk writes in Divrei Hayamim 1, 29: 23 "Vayeishev Sh'lomoh al Kisei Hashem le'Melech".
See Torah Temimah, note 17.
See Torah Temimah, note 19.
Why did Hashem spell the words "Keis" without an 'Alef', and why did he say "Kah" and not the full Name 'Havayah'?
Rashi and Ramban (citing Midrash Tanchuma): He swore that neither His Name nor His Throne will be complete until the Name of Amalek is erased. 1
As the Pasuk indicates in Tehilim, 9:7 & 8 (Rashi).
What are the implications of the words "mi'Dor Dor"?
Rashi (in Yeshayah, 34:10): It implies that from the generation of Moshe until the generation of Shaul, and from the generation of Shaul until that of Melech ha'Mashi'ach. 1
Ramban: It implies hat every king of Yisrael is obligated to take the battle against Amalek.
Targum Onkelos: It means that Hashem wwill destrroy Amalek from all the generations of the world.
Targum Yonasan: It means that Hashem swore that He would destroy Amalek from three generations - 1. from this world; 2. from the generation of Mashi'ach 2 and 3. from Olam ha'Ba (after Techi'as ha'Meisim).
Mechilta: Hashem swore by His Throne that if someone comes from any one of the nations to convert, one saccepts him - but not from Amalek and his family. 3
See also Ba'al ha'Turim.
See Na'ar Yonasan.
See Torah Temimah, note 20 - that the Mechilta learns this from the fact that the words miDor Dor" are written withou a 'Vav', and, bearing in mind that 'Daled' and 'Gimel' are interchangeable, "Dor" can be read as 'Ger'. See Torah Temimah, who elaborates.
Why is Amalek punished more than all the other nations who attacked Yisrael?
Ramban: Because all the other nations stood in awe of Hashem when they heard about the miracles of K'ri'as Yam-Suf, 1 whereas Amalek came from afar to attack Yisrael in total defiance of Hashem. 2
As the Torah described above - in Beshalach Sh'mos, 15:14 & 15.
As the Torah testifies in Devarim 25:18 - "and he did not fear Hashem" (Ramban).
