Siman 674

One may light a Hanukkah candle from a Hanukkah candle, and there is no degradation of the mitzvah in this, for he is lighting holy from holy. And even though one could say that this is like weakening the mitzvah, in that he takes a bit of oil from the candle by lighting another from it—this is nothing, for nothing was taken from it, and we are not concerned about this at all. And specifically to light from this one to that one without an intermediary. But to light from this one to that one by means of a mundane candle, meaning to light a mundane candle from a Hanukkah candle, this is certainly forbidden for there is a degradation of the mitzvah in this, as the holy serves the mundane; rather, even if his intention is to light the other Hanukkah candle with the mundane one—nevertheless it is forbidden, for at the time the mundane one is burning from it, there is a degradation for that moment. And there are those who permit even in such a case. And there is no degradation of the mitzvah here, since the intention is to light the Hanukkah candle from it. (And this depends on the Sugya of the Shas 22a, where we hold like Shmuel that one may light from candle to candle. And they disagree regarding an intermediary splinter like those who permit. And those who forbid hold that they disagree regarding candle to candle. And Rav who forbids—it is because of weakening the mitzvah. And even though he was refuted, it was not a complete refutation, as the Tosafot wrote in the comment beginning "What was the outcome" and in the Rosh ibid. And see Beit Yosef.)

And even according to the opinion of the one who permits it, if there is a concern that the mundane candle will be extinguished before he lights the Hanukkah candle from it – it is forbidden, because then it will only be a mundane use, and there is a degradation of the mitzvah. And there is one who permits even in such a case, for why should we be concerned for this? And even if perhaps it should come to this, what degradation is there in this? For behold, he lit it for the sake of the holy (Taz, subsection 2). However, our teacher, the Rema, wrote that the custom is to be stringent regarding Hanukkah candles, not to light even from candle to candle, for the essence of its mitzvah is only one candle, and the rest are not so much for the mitzvah. Therefore, one should not light one from the other. Thus far his words. And certainly if one of the candles was extinguished, one should not light it from another Hanukkah candle, for there is no mitzvah in its lighting, as we maintain: if it was extinguished – he is not bound by it, as I wrote in the previous siman (Magen Avraham). And in truth, all these reasons are weak. For since the essence of the prohibition is due to degradation of the mitzvah – behold, there is no degradation here in any event, for in any event it is a candle of a mitzvah. But since the custom is so – one should not change it. And certainly it is forbidden to light the shamash from a Hanukkah candle, in which there is no mitzvah at all, and this is forbidden by the law. And know that all this is within the time of its required measure. But after the time of its required measure – its sanctity has departed, and it is permitted to light from it even a mundane candle. For behold, it is permitted to extinguish it, as I wrote in siman 672. And it is permitted to benefit from it, and certainly it is permitted to light from it.

A candle of a mitzvah – it is permitted to light from a Chanukah candle according to the essential law, for example: to study before it or to pray. Therefore, in the beit din – all the candles burning there are of a mitzvah, and it is permitted to light one from another. Therefore, one lights in the beit knesset one candle from another, whether among the candles of the beit knesset, whether of Shabbat or of Chanukah. And one lights one from another and another from one, for they are all of a mitzvah. And it is forbidden to light a candle of a commoner from the candles of the beit knesset, and it was explained in siman 154, see there. (The Gra in subsection 5 wrote: that this which permits lighting one from another in the candles of the beit knesset – this is according to the one who permits lighting from candle to candle by means of a wood splinter. But according to the one who forbids it because of disparagement of a mitzvah – it is forbidden, for mitzvot nullify one another, and it is a disparagement of a mitzvah, see there. And I do not understand how this relates to "mitzvot nullify one another," for in any event this is certainly not a disparagement. And though the Ran wrote this reasoning regarding the use of a Chanukah candle for a matter of a mitzvah, he wrote the primary reason based on the fact that they made it a likeness to the Menorah, see there. Furthermore: use is different, and it requires further study. And also what the Magen Avraham wrote, that in our Mordechai he forbids in all candles of a mitzvah to light one from another, see there; it must be said that his intention is by means of a wood splinter, as the Pri Megadim wrote. See there, and in the Mordechai, and in the gloss of our teacher, the M. Tiktin. And the Mordechai is dealing there with a wood splinter, but if so, the words of the Magen Avraham require further study, for there is no contradiction here at all. Examine it and you will find it easy.)