'Rashi': They will say that Hashem is Elokim to Yisrael, and He fulfilled His word; Beis David is proper in front of Him.

Malbim: Beis David being proper in front of You will aggrandize His name, and counter Chilul Hashem that normally comes due to exile.

Malbim (Shmuel II, 7:26): Hashem will conduct with them wondrously, based on Hashgachah. Just like Hashem arranged nature, and Heavenly bodies do not deviate, so He arranged miraculous conduct [of the world] based on the actions of Am Hashem and His Avodah, which override the entire Heavenly Ma'areches (arrangement). Hashem does so Himself without an intermediary, and via this it is known that He is the Master and Conductor. Just like in the natural conduct, the sun rules over Ma'areches Shamayim and is head of all the stars that come out through it, so in the miraculous conduct via Yisrael, He prepared Beis David. Its throne corresponds to the sun. It conducts Hashem's Ma'areches just like the sun conducts Ma'areches Shamayim and all go around it. And just like the Kelim used to conduct the natural conduct last forever, it is proper that the Kelim used to conduct based on Hashgachah be eternal, i.e. Beis Yisrael and Beis David. Yirmeyah (31:35-36, 33:20-21) said "Nosen Shemesh l'Or Yomam...; Im Yamushu ha'Chukim ha'Eleh... Gam Zera Yisrael Yishbesu", "Im Tafru Es Briss ha'Yom...; Gam Brisi Sufar Es David."

Malbim (Shmuel II, 7:26): Via Yisrael, He is known to be Elokim who conducts the special conduct according to His desire. ¹