Midrash su Levitico 5:10

5) (Vayikra 5:8) "and he shall bring them": A bird (that became defective) cannot be redeemed (and replaced with another bird with its monies). ("And he shall bring them) to the Cohein": The burden of getting them (to the Cohein) is his. "And he shall sacrifice the one for the sin-offering first": What are we taught hereby? If that the sin-offering precedes the burnt-offering in all of its operations, is this not explicitly stated (Vayikra 5:10): "And the second one he shall make a burnt-offering as prescribed (Vayikra 1:14)"? Why, then, need this be repeated? To serve as a prototype (binyan av, see Hermeneutical Principles [Vayikra 1:3]) for all sin-offerings accompanied by burnt-offerings:

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 5:10) "And the second one he shall make a burnt-offering as prescribed": As prescribed for the sin-offering of a beast or as prescribed for the sin-offering of a bird, (that does not require sundering in its "pinching," viz. Vayikra 5:7) above)? (Vayikra 1:15) "And the Cohein shall bring it" (a bird burnt-offering — as distinct from the "pinching" of a bird sin-offering (Vayikra 5:8) —) distinguishes a burnt-offering from a sin-offering. For you could say "as prescribed for the sin-offering of a beast" — Just as the sin-offering of a beast comes from chullin (mundane monies, and not from monies of the second tithe), and (is sacrificed only in) the daytime, and (only with) the right hand, so (do these apply to) a bird burnt-offering. R. Yishmael says: "As prescribed" (means) as prescribed for the sin-offering of a bird, (which precedes [Vayikra 5:8]). Just as with the sin-offering of a bird — "opposite its nape," so with the burnt-offering of a bird, opposite its nape. R. Elazar b. R. Shimon says: As prescribed for the sin-offering of a bird. Just as with the sin-offering of a bird, he holds its head and its body and sprinkles (viz. Vayikra 5:9), so (does he do) with the burnt-offering of a bird. I might think that just as there (with the sin-offering of a bird), (only) one sign (is severed), here, too, (with the burnt-offering of a bird), (only) one sign should be severed. It is, therefore, (to negate this) written (in respect to the donative burnt-offering of a bird [Vayikra 1:15]): "And he shall bring it," (and not the prescribed burnt-offering of a bird — our case — with the severing of the two signs).