What is the grammatical form of "Hakshivah"?
Radak: It is Po'el Yotzei (it acts on others; make Your ears heed). And so it says "Lehakshiv la'Chachmah Aznecha" (Mishlei 2:2), "Takshiv Aznecha" (new, 10:17). [Hakshiv] is followed by [the prefix] Lamed, 'El' or [the prefix] Beis. Sometimes it is not connected [to a noun], e.g. "Hikshavti va'Eshma", "Mi Hikshiv Devaro" (Yirmeyah 8:6, 23:18).
What is "Shav'i"?
Malbim: It is my screaming for salvation and praying about an affliction that occurred to me. One of conditions for a complete Tefilah is that it is for pressing matters.
Why did he say "Malki vEi'lokai"?
Radak: You are my King - I scream to You like people scream to the king. You are Elokai - You are my Judge, and save me from those who do evil to me.
Why did he say "Ki Elecha Espalel"?
Radak: There is no one else who can save, for there is no [Power] other than You.
Malbim: I put my trust only in You. I do not add to Tefilah dependence on people or intermediaries between me and Hashem. This is the last condition for a complete Tefilah.
