Whom does he tell to trust in Hashem?
Radak: People in Galus.
Malbim: The nation (Yisrael).
Why does it say "b'Chol Es"?
Radak: Even though the time of Galus has lengthened, and redemption has not come, trust in Him at all times that He will bring the redemption.
Malbim: One who trusts in something else, e.g. people, it is not at all times; others cannot save at a time of evil. On Hashem, one trusts at all times.
What is "Am"?
Radak: It is Am Elokim.
How should they pour their hearts in front of Him?
Radak: They should repent with a full heart, and then He will bring the redeemer.
Malbim: They should reveal everything in their hearts. One who trusts in people cannot do so, for there are matters that they are embarrassed to say.
Why does it say "Ki Elokim Machaseh"?
Radak: He will not be a false refuge, like the refuge of people. This is why it says afterwards "Ach Hevel Bnei Adam" (verse 10)!
Malbim: Some trust in people, but people are not a shelter. Only Hashem is a shelter - "Tov Lachasos ba'Shem mi'Beto'ach ba'Adam" (118:9).
