What is the meaning of "His'halelu b'Shem Kadsho"?
'Rashi': Say that whoever trusts in our G-d, He will help us. This is like "bi'Kdosh Yisrael Tis'halel" (Yeshayah 41:16). We have a G-d Kadosh. This is like "ka'Shem Elokeinu b'Chol Kar'einu Elav" (Devarim 4:7).
Rashi (Tehilim 105:3): Glorify yourselves in the strength of His Kadosh name, that you have a patron like Him.
Radak (here and Tehilim 105:3): You can boast over all the nations in His Kadosh name that is Hukdash on you, just like it was sanctified through the matter of the Aron.
Vilna Gaon: Glorify yourselves that you merited to mention His Kadosh name like it is written, i.e. in the Mikdash. "Yivtach b'Shem Hashem" (Yeshayah 50:10), in the merit that you mention it. The Sifri (Devarim 62) expounds Birkas Kohanim in the Mikdash from "v'Samu Es Shmi" (Bamidbar 6:27), and outside the Mikdash from "b'Chol Makom Asher Azkir Es Shmi" (Shemos 20:21); there it is only a Zecher of His name. Also this is enough to save ? "Elu va'Rechev v'Eleh va'Susim va'Anachnu b'Shem Hashem Elokeinu Nazkir" (Tehilim 20:8)
Malbim (Tehilim 105:3): Shem Kadsho is His conduct in Kodesh, which is separated from fixed natural laws, to wondrous Kadosh conduct. This is according to Yisrael's Kedushah and their deeds, which also sanctifies His name ? "v'Nikdashti b'Soch Bnei Yisrael" (Vayikra 22:32). This is praise of Yisrael, that Hashem's name is sanctified via their Kedushah!
Who should rejoice?
'Rashi': Those who seek Hashem with a full heart.
Radak #1: Jews who seek Hashem.
Radak #2: Those who seek Hashem, even from other nations.
Why should they rejoice?
Radak: It is because they seek Hashem.
Vilna Gaon: Even those who mention His name not like it is written, may glorify themselves, for this suffices to save (refer to 16:10:1:4). All the more so, those who seek Hashem should rejoice!
Malbim (Tehilim 105:3): They will see that He is found to those who seek Him, and conducts with them according to their Midos. Normally, one who seeks something does not rejoice until he gets it ? either because it is a Safek if he will get it, or because he did not yet get his goal. Those who seek Hashem rejoice - either because they will surely get their goal, for He is found to those who seek Him, or because seeking Him is itself the purpose. One will never attain Him, just he will constantly seek. This is the purpose!
