Reference for Shevuot 22:8

אלא שאני פרה הואיל ודמיה יקרין

The red heifer defiles the defilement of edibles,<span class="x" onmousemove="('comment',' After it has been slaughtered, its flesh can become unclean by contact with the carcass of an unclean animal (or clean animal not ritually killed) , and it can then make edibles unclean by contact. Although the enjoyment of any kind of benefit from it is prohibited, and, according to R. Simeon, only edibles that are permitted are considered edibles capable of receiving and transmitting defilement (Men. 101b) , it is, nevertheless, counted as an edible, because there was a time when the use of it might have been permitted, as explained infra. If it be asked, surely the flesh of the red heifer itself defiles without contact with a carcass, v. Hul. 82a, Rashi; B.K. 77a, Tosaf., for an explanation.');">¹⁸</span> because it had a period of fitness.'<span class="x" onmousemove="('comment',' I.e., capable of being counted fit as an edible.');">¹⁹</span> And R'Simeon B'Lakish said: R'Simeon used to say that the red heifer may be redeemed [even] on its woodpile!'<span class="x" onmousemove="('comment',' I.e., if a better one was obtainable, the heifer could be redeemed even after having been ritually slaughtered. This is the period of fitness to which R. Simeon alludes, and in virtue of which the flesh is regarded by him as an edible; R. Simeon holding that whatever is capable of being redeemed is counted as if it were redeemed. How, then, can the Baraitha be in accordance with R. Simeon's view, since the last clause in it states that if he slaughtered it on its wood-pile it can never be redeemed?');">²⁰</span>

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