What is the significance of "l'Olam Teshev"?
Rav Sadya Gaon: You exist forever. Rashi - therefore, "Lamah la'Netzach Tishkachenu" (20)? You swore to us Bach 1 (in You Yourself). Just like You persist [forever], also Your Shevu'ah!
Ibn Ezra: We know that Your kingship will never depart. For all generations You sit on the throne.
Palgei Mayim: Now, Hashem's name is not complete, and the throne is not complete 2 . My request is that the name and throne be complete!
Rashi (Shemos 32:13): You said "Bi Nishbati" (Bereishis 22:16). Ri Kara - [even] if "Har Tziyon she'Shamem" (18), You dwell forever. The Shevu'ah was in You!
Shemos 17:16: "Ki Yad Al Kes Kah"; Rashi (there, from Midrash Tanchuma) - His name and throne will not be complete until Amalek's name is totally erased.
