What is "l'Tzur Ma'on"?
Radak: David fled from his residence in Yerushalayim due to his son; he asked Hashem to be for him a strong residence in which he can take refuge from his son.
Malbim: In my youth, You were for me l'Tzur Ma'on, like he said in Mizmor 31 1 . If so, it is proper that I enter this Tzur Ma'on always, and also now I should take refuge in it.
Verse 3 - however, there it says "l'Tzur Ma'oz" (PF).
What is the meaning of "Lavo Samid"?
Rashi: I will always come in that dwelling, to be saved in it from the pursuer.
Malbim: Your command was that I always come to this rock so You will save me in it. You did not command to come temporarily, rather, permanently, "Ki Sal'i u'Metzudasi Atah." Until now repeats what he said in his youth when he fled Sha'ul; now his Tefilah begins.
Why did he say "Tzivisa Lehoshi'eni"?
Rashi: Many times You saved me via Your Sheluchim.
Radak #1: This is like Tetzaveh; past tense used in place of future (like is common in Nevu'ah).
Radak #2: You commanded many times to save me. So save me now! The command is to angels - "Ki Mal'achav Yetzaveh Lach Lishmarcha b'Chol Derachecha" (91:11).
