Reference for Pesachim 31:3
וסבר רבי אלעזר משקין אית להו טומאה בעולם והתניא ר"א אומר אין טומאה למשקין כל עיקר תדע שהרי העיד יוסי בן יועזר איש צרידה על איל קומציא דכי ועל משקי בית מטבחיא דכן
R'Jose and R'Simeon maintain: In respect of eatables, they are unclean; in respect of utensils they are clean.<span class="x" onmousemove="('comment',' The general principle is this: when a doubt arises in a Scriptural law, we are stringent; in a Rabbinical law, we are lenient. Now liquid can become defiled by Scriptural law (Lev. XI, 34) , hence in doubt it is unclean. But there is a controversy as to whether it can defile other objects by Scriptural law. R. Meir holds that it cannot defile either food or utensils; R. Judah that it defiles both; while R. Jose and R. Simeon hold that it defiles food but not utensils.');"><sup>3</sup></span> But does R'Eleazar hold that liquid is at all susceptible to uncleanness,<span class="x" onmousemove="('comment',' Even in respect of itself.');"><sup>4</sup></span>