TT #225 · Parshas Shemini · Aliyah 7 · Passuk 39
Chabad.org — Vayikra Chapter 11 with Rashi
English: “When it dies”: a carcass conveys impurity while moist, but not once it is dry, because the verse speaks of a state resembling death.
Niddah 56a.
E-Daf.com — Niddah 56a (Tsurras Hadaf)
Textual definition — The Chazal derives the stated rule from the wording and comparison in the verse.
The carcass impurity described here applies while moist.