(Bamidbar, Ibid.) "It (the heifer) is a sin-offering.": We are hereby apprised that it is subject to me'ilah (abuse of what is sacred, as a sin-offering is). "it": It (the heifer) is subject to me'ilah, but not its ashes. Variantly: "It is a sin-offering": We are hereby apprised that if it is not slaughtered to its specific end, it is unfit. Variantly: "It is a sin-offering": We are hereby apprised that it (like a sin-offering) is not burned at night as it is in the daytime.
If "it is a sin-offering," I might think that it is voided by being kept overnight; it is, therefore, written "And it shall be for the congregation of the children of Israel in keeping." We are hereby apprised that it "keeps" day after day and year after year. (Ibid. 10) "And he who gathers the ashes of the heifer shall wash his garments": We are hereby taught about the gatherer of the heifer's ashes that he confers tumah upon his clothing. — But even without the verse, I would know it a fortiori, viz.: If the burner (of the heifer) confers tumah upon his clothing, how much more so, the gatherer (of its ashes)! (Why, then, is the verse needed?)
The verse, rather, tells us that he who gathers the ashes becomes tamei (even) by hesset (i.e., merely by moving them, even though he does not touch them.) "And it shall be for the children of Israel and for the sojourner who dwells in their midst": Because the command is to Israel, the proselytes must be (explicitly) included. "as an everlasting statute": that it obtain for succeeding generations.