Reference for Bekhorot 84:20
ורבי אלעזר כמאן סברא כי הא דאמר ריש לקיש
And as regards R'Elai whose view does he follow? - It is that of Resh Lakish [as follows]: The ruling that a tumtum is a doubtful case [as regards sex] relates only to a human being, since his male and female parts are in the same place.<span class="x" onmousemove="('comment',' Urination therefore does not provide a test. In the case of a tumtum animal, however, there need be no doubt as to its sex according to all the authorities concerned. The first Tanna in the Mishnah who says that the animal must not be slaughtered, refers to where it urinates in the male part, and then it is assuredly holy and therefore it must not be slaughtered outside the Temple. It is also not suitable for sacrifice in the Temple, for it has the appearance of a blemished animal, as it does not possess male genitals, a defect which Scripture excludes by the text 'A male'. And both R. Ishmael and the last Rabbis only refer to a hermaphrodite, but as regards a tumtum they are all agreed that if the animal urinates in the male part, then it is a male, and if in the female part, then it is a female. R. Elai's decision will thus be in accordance with the views of all the authorities concerned. Tosaf. however maintains that Resh Lakish's view will not be shared by all the authorities; the ruling of the first Tanna of the Mishnah, for example, that it is a doubtful animal, will not be in accordance with the view of Resh Lakish who will concur with the view of R. Simeon b. Judah. .');"><sup>13</sup></span>