Midrash su Levitico 27:22

4) (Vayikra 27:22) ("And if the field of his acquisition [from another], which is not of the field of his [family] holding, he shall consecrate to the L–rd, [and he comes to redeem it],") What is the intent of this? If one acquired a field from his father, and his father died, and then he consecrated it, I might think that it is reckoned as a field of acquisition; it is, therefore, written "which is not of the field of his (family) holding" — a field which is not a field of holding, to exclude this, which is a field of holding. These are the words of R. Meir. R. Yehudah and R. Shimon say: If one acquired a field from his father, and he consecrated it and then his father died, I might think that it is reckoned as a field of acquisition; it is, therefore, written "which is not of the field of his holding" — a field which was not fit to be a field of holding, to exclude this, which was fit to be a field of holding. A field of acquisition (which was consecrated and not redeemed) does not revert to the Cohanim on Yovel, for one cannot consecrate something that is not his. (Vayikra 27:23) ("Then the Cohein shall reckon for him michsath your valuation until the Jubilee year, and he shall give your valuation on that day; it is holy to the L–rd.") "Then the Cohein shall reckon for him 'michsath'": michsath connotes "amount of money," i.e., he gives what it is worth.

5) R. Elazar said: It is written here "Then he shall reckon" and elsewhere (Vayikra 27:18) "Then he shall reckon." Just as there, he gives the sowing of a chomer of barley for fifty silver shekels, so, here.

6) "and he shall give your valuation on that day": He should not delay (in expectation of a higher valuation later). For even if the poorest of men has a precious jewel, (which might fetch a very high price elsewhere), he is valuated only according to his present place and time.