1)
What is the purpose of this Mizmor?
1.
Malbim: It explains that intellect obligates that one who trusts in Hashem, Chesed will surround him. Such people will surely find in Him shelter and strength.
2)
What is the comparison to Har Tziyon?
1.
Rashi: Those who trust in Hashem will not falter, just like Har Tziyon, for "just like mountain surround Yerushalayim, Hashem is around His nation" (2).
3)
Why does it say "l'Olam Yeshev"?
1.
Radak: When the Galus returns, it will never falter or be destroyed [again]. It will exist forever. Similarly, "v'Atah Kadosh Yoshev" - You exist forever.
