Midrash su Levitico 14:7

1) (Vayikra 14:7) ("And he shall sprinkle upon the one to be cleansed from the leprosy seven times, and he shall cleanse him, and he shall send the living bird over the face of the field.") "And he shall sprinkle": on the upper surface of the leper's hand, and others say on his forehead. "And he shall sprinkle upon the one to be cleansed from the leprosy seven times": The one to be cleansed from the leprosy requires seven sprinklings; one (who is to be cleansed from) dead body uncleanliness does not require seven sprinklings.

2) (The verse is needed for the above, for without it we would say) Does it not follow a fortiori that he does require seven sprinklings, viz.: If a leper, who does not require sprinkling on the third and seventh day (viz. Bamidbar 19:12) requires seven sprinklings, then one who is tamei through a dead body, who does require sprinkling on the third and seventh day — how much more so does he require seven sprinklings! It must, therefore, be written "And he shall sprinkle upon the one to be cleansed from the leprosy." The one to be cleansed from the leprosy requires seven sprinklings; one (who is to be cleansed from) dead body uncleanliness does not require seven sprinklings.

3) But let it follow a fortiori that a leper requires sprinkling on the third and seventh day, viz.: If one who is tamei through a dead body, who does not require seven sprinklings, requires sprinkling on the third and seventh day, then a leper, who does require seven sprinklings, how much more so should he require sprinkling on the third and seventh day! It is, therefore, written "seven times and he shall cleanse him." He requires (for cleansing) seven sprinklings; he does not require sprinkling on the third and seventh day.