The letter מ that is added to the beginning of nouns - like משכן, מושב, מקדש, מרכב, משכב, מקום - indicates a special place for a certain matter. And therefore, they explain when it is written, חוץ למחנה מושבו (without the camp shall his dwelling be)¹⁷, that מושבו (his dwelling) is unclean, since it did not say שבתו. And when it is written לכל מראה עיני הכהן (as far as appears to the priest)¹⁸, but it does not say לכל ראות, it teaches not to rule according to the perceiver, but rather according to the objective appearance.

footnotes: ¹⁷ Leviticus 13:46. ¹⁸ Leviticus 13:12.

And moreover, the letter מ indicates the instrument with which the action is performed, like משקל, מקטר, מבטח, מבצר. It means to say the object which is made for weighing, a scale (משקל), or for burning incense (מקטר). And this is what distinguishes them from the nouns שקל, קדש, קיטר, ביטחון, בצרון, which indicate the thing itself. And this is the difference between מכר and ממכר (merchandise); the noun ממכר also includes a gift. And moreover, between מקנה and קנין (acquisition); the noun מקנה emphasizes the action of acquisition, while the noun קנין is a noun representing the abstraction of acquisition, without focusing on the action.