Commentary for Numbers 19:9

והניח מחוץ למחנה AND HE SHALL LAY THEM UP WITHOUT THE CAMP — He divided it (the ashes) into three portions: one he placed on Mount Olivet, another was divided between all the priestly divisions, and the other he placed in the חיל (the space that surrounded the Temple area) (Sifrei Bamidbar 124:1; Mishnah Parah 3:11). That portion given to the priestly divisions was outside the forecourt, so that the inhabitants of the cities and anyone who required to be cleansed might take of it; as for that which was on the Mount of Olives, the High Priests purified themselves by means of it for preparing other “red cows”, whilst that which was in the space surrounding the Temple area was placed there to be kept for all times by special enactment of Scripture, as it is said, “and it shall be kept for the congregation of the children of Israel" (cf. Tosefta Parah 3 8).

[He divided it] into three parts. As we learned in the third chapter of Parah (Mishnah 11), and Tosafos explains “three parts” as does Rashi. Re”m writes: It seems to me that the division into three parts was by tradition. For although the verse first states "A ritually pure man shall gather, etc." (v. 9), it repeats and says "It shall remain [a keepsake]" for the community of Bnei Yisroel (ibid.) to let us know what shall be done with it by putting it down in a clean place. The third verse that states, "It shall be for Bnei Yisroel and for the proselyte who lives among them," etc. (v. 10) is to let us know that this law shall always be carried out according to this order.

V. 9. איש להכשיר את הזר, טהור להכשיר את האשה, והניח מי שיש בו דעת ,ואסף איש וגו׳ להניח יצאו חרש שוטה וקטן. Zum Sammeln der Asche bedarfs keines כהן, jeder erwachsene vollsinnige Mensch ist dazu befähigt. Ebenso darf dies Einsammeln auch nachts geschehen und das gleichzeitige Vornehmen einer anderen מלאכת stört nicht die Gültigkeit, אין מלאכה פוסלת בה (Para 4, 4).