The Gemara in Masekhet Shabbat (21a-b) cites a famous debate among the Amoraim as to whether the Chanukah lights are subject to the same specifications as the weekly Shabbat candles. Chazal forbade the use of certain oils and wicks for the weekly Shabbat candle lighting, as those oils and wicks produce an unsteady flame, and thus one might forgetfully tilt the lamp on Shabbat when the candle flickers, in violation of Shabbat. According to Rav Huna, these materials may not be used for the Chanukah lights, either, since the candle might be extinguished before burning the requisite period. The accepted opinion (Shulchan Arukh, O.C. 673:1), however, that of Rav, permits the use of these wicks and oils for the Chanukah candles, despite the possibility that the candles might be extinguished. The Gemara explains that according to Rav, Halakha does not require one to rekindle the Chanukah lights if they are extinguished. In his view, therefore, it does not concern us if the candles are extinguished at some point after they are lit, since the obligation was fulfilled already by their kindling. Rav Huna, however, maintained that one must rekindle Chanukah lights that were extinguished, and he therefore requires lighting with oils and wicks that produce a steady, reliable flame that has little possibility of being extinguished, lest one neglect to rekindle an extinguished flame.
The Penei Yehoshua comments that even Rav Huna would permit kindling with the disqualified oils and wicks when other materials are not available. Since Chazal disqualified these materials only as a safeguard, to protect against the possibility of the lights being extinguished and the individual neglecting to rekindle them, this provision should not apply at the expense of the mitzva’s fulfillment. Therefore, if one finds himself with only candles and wicks which are – in Rav Huna’s view – disqualified for use, Rav Huna would permit, and presumably require, the individual to light the candles with these materials.
While the Penei Yehoshua’s remark may, at first, seem perfectly reasonable and intuitive, this issue may, in truth, be more complex. Rav Natan Gestetner, in his Natan Piryo – Chanukah (p. 3), raises the possibility that the Penei Yehoshua’s claim may hinge on an interesting question regarding the recitation of the nighttime Shema. Torah law allows fulfilling the nighttime Shema obligation anytime during the night, but Chazal required reciting the text before midnight (as defined by Halakha), as a safeguard against forgetting to fulfill the obligation. Rabbenu Yona (Berakhot 2a), surprisingly, posits that one who did not recite Shema before midnight can no longer fulfill the obligation. Although the person is still bound by the Torah obligation to read Shema, nevertheless, the Sages have the authority to suspend this Torah obligation for the sake of enforcing their safeguard. The Sha’agat Aryeh (4) disagrees, claiming that one should not forfeit the Torah obligation of Shema just because he failed to abide by Chazal’s provision. Seemingly, Rav Gestetner suggests, this debate would affect the case addressed by the Penei Yehoshua. According to Rabbenu Yona, we might assume that once Chazal forbade the use of certain wicks and oils for the Chanukah lights as a safeguard to ensure the proper performance of the mitzva, it applies even at the expense of the mitzva’s fulfillment. And thus even if one has only these materials, he does not light the candles, since he cannot observe the mitzva as prescribed by Chazal.
Rav Gestetner then proceeds to distinguish between one who knowingly or neglectfully failed to observe the rabbinically ordained requirement, and one who is unable to do so. In the case addressed by Rabbenu Yona and the Sha’agat Aryeh, the individual failed to recite the Shema by the deadline established by Chazal, and it is thus perhaps for this reason that, according to Rabbenu Yona, he is penalized and not allowed to fulfill the mitzva afterward. In the case discussed by the Penei Yehoshua, however, the person finds himself without the materials required by Chazal, and has entered this situation for no fault of his own. In this instance, Rav Gestetner suggests, even Rabbenu Yona would agree that the individual should light the Chanukah candles with the forbidden materials, rather than forfeit the mitzva altogether. However, if he has suitable oil and wicks, but for whatever reason lit with the disqualified materials, then, according to Rabbenu Yona, he has not fulfilled the mitzva at all, and must light again afterward with the acceptable materials.
Rav Gestetner then addresses the intriguing case where one had only the disqualified materials, but after lighting the candles with these materials, he obtains suitable oil and wicks. One could argue that in this case, since the person lit properly given the circumstances, he has fulfilled the mitzva and would not then be required to light again when he receives the proper materials. Although Rav Gestetner advances this argument, he leaves the question unresolved, acknowledging the possibility that the individual in this case would be required to perform the mitzva anew with the proper oil and wicks.
We must emphasize that this entire discussion relates to the position of Rav Huna, who requires using for Chanukah candles only those oils and wicks which are suitable for Shabbat candles. The accepted halakha, as mentioned, does not follow this view.