Siman 678

In siman 263 it was explained that regarding the Shabbat lamp and the kiddush of the day—the Shabbat lamp is preferable if his hand cannot reach both, for peace of the home is preferable to all things. And the Shabbat lamp constitutes peace of the home, so that they do not sit in darkness and stumble in their walking, see there. And all the more so that the Shabbat lamp takes precedence over the Hanukkah lamp, for the kiddush of the day is from the Torah. And even though he could recite kiddush over bread, nevertheless if he also does not have bread—the Shabbat lamp is preferable. And all the more so against the Hanukkah lamp which is rabbinic. And even though many poskim hold that kiddush as well is only rabbinic, and from the Torah one fulfills the obligation through prayer, nevertheless its essence is from the Torah. And even though with the Hanukkah lamp there is the publication of the miracle, nevertheless peace of the home is greater than all of them. However, one lamp suffices for peace of the home, and with the remainder he should buy a Hanukkah lamp (Magen Avraham).

And if he has a Shabbat candle, but he does not have wine for kiddush if he buys a Chanukah candle—the Chanukah candle takes precedence, because of pirsumei nisa. And specifically when he has bread. But if he does not have bread—bread takes precedence even according to the one who holds that it is rabbinic, for lechem mishneh is from the Torah (Taz). And there is one who says that even against bread, the Chanukah candle takes precedence (Bach). And it appears like the first opinion: for even if we say that this is not from the Torah, nevertheless, with bread there is certainly also shalom bayit, as is understood. And so too, a Chanukah candle takes precedence over havdalah. However, even regarding the Chanukah candle, when he has one candle—it is enough, and with the remainder he should buy wine for kiddush and for havdalah, since according to the law he fulfills the obligation with one candle.

There is one who says that in this time, when we light the Hanukkah candle inside the house, one should not say that the Shabbat candle is preferable, and it is better to light the Hanukkah candle and automatically there will be light in the house. And even though it is forbidden to eat by its light, nevertheless it is better to eat opposite it than to nullify the Hanukkah candle entirely, since it is impossible otherwise (Magen Avraham). And there is one who disagrees with this (Eliyah Rabbah). Nevertheless, one may rely on this in a time of pressing need, for regarding the primary use, there are those who say that use for a mitzvah is permitted, as I wrote in siman 673, and the Shabbat meal is certainly a mitzvah meal.