Reference for Pesachim 41:7
<br><br><big><strong>הדרן עלך אור לארבעה עשר</strong></big><br><br>
is unclean; you might say,Let us enact a preventive measure lest its outside touch the terumah. Therefore he informs us [otherwise].<span class="x" onmousemove="('comment',' Thus 'R. Eliezer concedes to R. Joshua' applies not to the second clause but to the first, where it is stated that if he can save a rebi'ith in purity he must do so. Thereupon we are told that even if the outside of the vessel in which it is to be saved is unclean, so that there is the slight possibility of the terumah falling thereon and becoming contaminated, yet R. Eliezer, who rules that in no circumstances is deliberate defilement permitted, admits that he may use this for saving the terumah. If unclean liquid falls on the outside of a vessel it contaminates the outside, but not the inside, since the uncleanness of a vessel through liquids is by Rabbinical law only.');"><sup>7</sup></span>