Why did he say "Ki Yitzpeneni b'Suko"?
Rashi: I am sure that He will hide me in His Beis ha'Mikdash. Seder Olam (18) expounds this regarding Yo'ash ben Achazyah. Achazyah's sister Yehosheva hid him in the Aliyah above Kodesh ha'Kodoshim - "va'Yhi Itah Beis Hashem Mischabei Shesh Shanim" (Melachim II, 11:3).
Radak: Now when I engage in bodily needs, He does good to me and gives to me my request, and hides me in His Sukah from a flood of enemies.
Malbim: Because I request only to sit in Beis Hashem, I am sure that He will hide me...
What is "b'Yom Ra'ah"?
Radak: My enemies thought to do evil to me.
What is the meaning of "b'Tzur Yeromemeni"?
Rashi: He stood my foot on the rock.
Radak: He hid me in a place where my enemies cannot reach me.
Malbim: Hiding me in His tent is as if He raises me on a rock, so my enemies cannot ascend to me.
