Musar zu Bamidbar 18:20

[And, in truth, just as we find that the Holy One Blessed be He sanctified the tribe of Levi and exhorted Israel not to forsake it, as it is written (Devarim 16:19): "Take heed unto yourself lest you forsake the Levite all of your days upon your land," so, it is, likewise, the will of the Blessed L-rd that we support men who separate themselves from the affairs of the world in order to serve the L-rd. For this is certainly not inferior to supporting the Levite in this regard. As Rambam writes (Hilchoth Shemitah Veyovel, Chapter 13 Halachah 12 and 13): "Why did the Levite not merit inheritance in Eretz Yisrael and in its spoils with his brothers? For he was singled out to serve the L-rd, to minister unto Him and to teach His just ways and righteous judgments to the people, as it is written (Devarim 33:10): 'They shall teach Your judgments to Jacob and Your Torah to Israel.' Therefore, they were separated from the ways of the world. They do not wage war, as do the rest of Israel, they do not inherit, and they do not merit things for themselves with the strength of their bodies, but they are "the army of the L-rd," as it is written (Ibid. 11): 'The L-rd bless his [Levi's] strength.' And the Holy One Blessed be He bequeaths [things] on them, as it is written (Numbers 18:20): 'I am your [Levi's] portion and your inheritance.' And [this applies] not only to the tribe of Levi alone, but to every man of all those who enter the world, whose spirit moves him, and who understands of himself to be separate, to stand before the L-rd, to minister unto Him and to serve Him, to know the L-rd and to walk justly, as G-d made him. And he divests himself of the many "accountings" that men seek, he is sanctified as "holy of holies," and the L-rd becomes his portion and his inheritance for ever and ever. And He bequeaths to him in this world what suffices him, as He did to the Cohanim and the Levites. As David, may peace be upon him said (Psalms 16:5): 'The L-rd is the portion of my inheritance.'" Until here, his (Rambam's) beautiful language.]