What is "Musari"?
Vayikra Rabah 30:1: It is the Musar of Torah.
Why should you take my Musar and not silver?
Malbim: Musar ha'Chachmah is compared to Kesef, Kesef is spent to buy everything needed. It has already been explained that Yir'as Hashem is Musar Chachmah (15:33). Since there are no proofs from Da'as for the laws of Chachmah, and the Yetzarim of man's heart opposite Chachmah, he must bind the powers of his Nefesh with Musar, which is Yir'as Hashem. Via this he receives the laws of Chachmah and guards them amidst fear of Hashem, who commanded about them. Musar Chachmah can be spent - via it, one acquires the laws of Chachmah and stores them in his heart - "Yir'as Hashem Hi Otzaro" (Yeshayah 33:6). Therefore, the verse commands to take Musar Chachmah, and not strive to acquire Kesef. For Kesef, one acquires matters of folly and temporary matters without real [importance]. For Musar Chachmah one acquires dear Segulos - Divrei Chachmah dearer than any object.
What is "Charutz"?
Rashi: It is a kind of gold.
Why is Da'as better than Charutz?
Malbim: Charutz (gold) is not spent. Rather, one stores it in a storehouse, for it is very dear. It is better to store Da'as, i.e. Da'as Elokim, the secret of His conduct and Hashgachah, and all dear Yedi'os. They fill the Nefesh with a storehouse full of all desired Kelim, worth more than Charutz, which is better than them only in appearance.
