What is "Misgav la'Dach"?
Rashi: [When His throne is prepared for Mishpat, He will be] a refuge for Yisrael, who are downtrodden.
Radak: [Whenever He judges the world,] He is a refuge for the poor. Even though the Oni is lowly without strength, Hashem does not leave him [to be oppressed via] those stronger than him. The Oni is elevated in Hashem like a person is elevated in a strong tower, just like Yisrael were elevated in Him today; He was for them like a strong tower.
Malbim: Hashem does not wait for the oppressor to do evil to the downtrodden. Rather, immediately He is a refuge for him. This is whether he is intrinsically downtrodden, or he is weak now due to the afflictions. Then, Hashem saves immediately due to mercy. For His nation Yisrael, Hashem does not wait until a time of affliction. For nations Hashem does Mishpat (verse 9), for the poor mercy, for Yisrael, love and dearness.
What are "l'Itos ba'Tzarah"?
Rashi: They are times of affliction. Yisrael are now in great affliction due to this Pelishti (Galyus) and Pelishtim, who were overpowering them - "Ki Ba'ah Tza'akaso Elai" (Shmuel I, 9:16).
