Why will they rejoice?
Malbim: Mevakshei Hashem are unlike those who seek something else. The latter is happy about the request only if he gets what he wanted. Seeking Hashem is itself the purpose!
Who are "Mevakshecha"?
Radak: They are people who request only Your salvation, and not from others.
Why will they say "Yigdal Hashem"?
Radak: When Hashem does miracles and Chasadim, He is Gadol.
Why does it say "Ohavei Teshu'asecha"?
Malbim: One who does not love the salvation itself, only that the affliction ended, he would prefer that there was no Tzarah and no need for salvation. Those who love the salvation, for it brings Kidush Hashem, they want to constantly need salvation, for then there is constantly Kidush Hashem!
