What is his Tefilah?
Radak: After I accepted Your rebuke, and I suffered affliction, cleanse me from my sin and cure me.
What is the difference between Tefilah and Shav'ah?
Malbim: Tefilah is pouring the Nefesh, intent of the heart and lifting the Ru'ach to Hashem. Shav'asi is my scream for salvation.
Why did he say not to be quiet to his tears?
Malbim: The gates of tears are never locked (Brachos 32b); they arouse mercy.
Why did he call himself a Ger?
Radak #1: Man in the world is like a Ger in a foreign land. He constantly travels from place to place. So man has no station in the world. He is called also Toshav, for he settles in the world as if he will be here many days.
Radak #2: Hear my Tefilah to make me live from my illness, for man's days here are few; he is considered like a stranger in the world.
Malbim: I am composed of two parts. My Nefesh is with You, a part of Yourself. I am a stranger in this land. The Nefesh is spiritual, in a physical land, far from its source and place. Also refer to 39:13:6:2.
Why does it say "Imach"?
Radak: This is in front of You; dwelling in the world and leaving it are in Your hand.
Why did he say "k'Chol Avosai"?
Radak: This is k'Chol Avoseinu. The latter generations are like the former. There is no difference between them.
Malbim: Based on my body I am a Toshav (resident in this world) like all My fathers. The body's root is from his ancestors, who gave birth to him. The body overpowers the Nefesh, for the latter is only a stranger - refer to 39:13:4:3.
