Commentary for Kiddushin 40:19

This baraita is brought as an objection against R. Sheshet. The baraita learns from a midrash that one may redeem half of a field that he has dedicated to the Temple (this is the same as above). But then it argues that from a logical perspective, just as one who sells his field cannot redeem half of it, so too one who dedicates his field cannot redeem half of it. This is the opposite of R. Shimon’s midrash from above.