מעשר שני אין שוקלין כנגדו דנרי זהב, ואפילו לחלל עליו מעשר שני אחר. אי אמרת בשלמא כי פליגי רב ושמואל מנר לנר אבל בקינסא אסר שמואל — הא לא תהוי תיובתא. אלא אי אמרת בקינסא נמי שרי — הא תהוי תיובתא! אמר רבה: גזירה שמא לא יכוין משקלותיו וקא מפיק להו לחולין.
the second tithe, one may not weigh gold dinars with it in order to determine their precise weight. And doing so is prohibited even if he is weighing the coin in order to redeem other second-tithe produce with it, as one may not derive benefit from tithe money. The Talmud discusses this matter: Granted, if you say that when Rav and Shmuel disagree it is with regard to a case when one lights from lamp to lamp, but with a wood chip, Shmuel prohibits lighting, this will not be a conclusive refutation of Shmuel’s opinion. But if you say that he permits lighting from lamp to lamp with a wood chip as well, this would be a conclusive refutation of his opinion, as the rabbis did not permit use of and benefit from a sacred object even for the purpose of a similar sacred need. Rabba said: This is not difficult, as in the case of weighing tithe money the rabbis prohibited doing so as a decree lest the weights not be precisely equal. One will discover that the weight of the gold dinars is not equal to the weight of the sela that he used to weigh them, and he will reconsider and render them unsanctified, i.e., they will maintain their original, non-sacred status. In that case, he will have used the tithe money for an unsanctified purpose. However, when one lights even a wood chip for the purpose of Hanukkah lights, it is clear that it is for the purpose of performing a mitzva, and there is no reason to issue a decree.