Midrash su Levitico 5:13

9) (In respect to a lamb, it is written (Vayikra 5:6) lit.,) "from his sin"; (in respect to a bird, Vayikra 5:10,) "from his sin," (and, in respect to the tenth of an ephah, Vayikra 5:13,) "on (i.e., in addition to) his sin." What is the intent of this? (The intent is that) One may bring from (the monies he set aside to) the sanctuary [hekdesh]: for a lamb, a goat-kid; for a goat-kid, a lamb; for a lamb or a goat-kid, turtle-doves or young pigeons; for turtle-doves or young pigeons, a tenth of an ephah.

10) (Vayikra 5:13): "And the Cohein shall make atonement for him, for his sin that he has sinned, of one of these." What is the intent of this ("of these")? For I might think: "The most stringent of them (tumah of the sanctuary and its consecrated objects) should be subject to lamb or goat-kid; the less stringent (a court-mandated oath), to a bird; the least stringent (an oath of "pronouncement"), to the tenth of an ephah. It is therefore, (to negate this) written "of one of these" — to equate the least stringent to the most stringent vis-à-vis lamb and goat-kid, and the most stringent to the least stringent vis-à-vis the tenth of en ephah.

11) (Vayikra 5:13): "and it shall be to the Cohein": That is, the meal-offering service of the Cohein (if he himself is the sinner) can be performed by the Cohein himself. Or perhaps its intent is only to permit (the eating of what remains of) the tenth of an ephah of a Cohein (who sinned). And how would I satisfy (Vayikra 6:16): "And every meal-offering of a Cohein shall be entire, (exclusively for the L–rd); it shall not be eaten"? By his donative meal-offering; but his one tenth of the ephah may be eaten. It is therefore, (to negate this) written ("and it shall be to the Cohein) as a meal-offering" — as his donative meal-offering. Just as his donative meal-offering is not eaten, so the tenth of the ephah is not eaten. R. Shimon says: "and it shall be to the Cohein as a meal-offering": The tenth of an ephah of a Cohein is like the tenth of the ephah of an Israelite, viz. Just as a fistful is taken of the tenth of the ephah of an Israelite, so a fistful is taken of this tenth of an ephah (of a Cohein).