Radak: They are the Kohanim and Leviyim. They are close to Hashem and always stand in front of Him. They should trust in Hashem, for their Avodah in front of Him will help them.

Malbim: One who has more than trust in Hashem and is at a higher level, so his help and protection will be greater. Beis Aharon have a higher level and trust than Beis Yisrael, so their help and protection will be greater.