פירוש על קידושין 49:7

Rabbi [Yehudah Hanasi] says that the slave goes free if he is castrated, but he does not seem to agree with Ben Azzai that he goes free if his tongue is cut off. But there is a baraita that seems to contradict this. This baraita is about sprinkling a person with the red heifer waters in order to purify him. According to Rabbi, if he is sprinkled in his mouth, which we at first interpret as on his tongue, then the sprinkling is considered valid. This implies that the tongue is an exposed organ and that a slave would go free if the master cut it off.