Our Sages (Shabbat 21b) disagreed regarding the most superior manner to perform the Mitzvah of lighting Chanukah candles. According to Bet Hillel, who the Halacha follows, one lights one candle on the first night and adds one candle every subsequent night for the duration of Chanukah.
Indeed, the Shulchan Aruch (Chapter 671) states: “How many candles should one light? On the first night, one should light one candle. On each subsequent night, one adds one candle per night such that on the eighth night, one will have lit eight candles. Even if there are many members of the household, one should not light more than this prescribed amount.”
Based on the above, the bare minimum to fulfill the Mitzvah of lighting Chanukah candles is to light one candle per night. Thus, a pauper who does not even have what to eat should sell his wares in order to purchase a small amount of oil or candles so that he may light one candle per night for the duration of Chanukah. This is because of how special the Mitzvah of lighting Chanukah candles is about which the Gemara (Shabbat 23a according to Rabbeinu Chananel’s text) states that one who is careful regarding the Mitzvah of lighting Chanukah candles shall merit having children who are Torah scholars. This is a more auspicious Segulah regarding the raising of one’s children in the path of Torah than many other Segulot.
In this generation, thanks to the tremendous abundance Hashem showers us with, it is very rare to hear about someone who does not have oil or candles to light the Chanukah lights with. Nevertheless, it does happen that one is traveling out of town and may not have enough candles to light the prescribed amount of lights and can only light one candle. Needless to say, one should light this one candle, for by doing so, one will fulfill one’s basic obligation of this Mitzvah.
The Poskim disagree regarding one who has only two candles on the third night of Chanukah. Should one light only one candle or should one light both of them in order to fulfill the Mitzvah in a more beautified manner with at least the one extra candle one has.
Maran Rabbeinu Ovadia Yosef zt”l proves clearly in his Chazon Ovadia- Chanukah (page 31) that only one candle should be lit in this situation, for adding candles in a way that does not correspond to the number of the day is not considered beautifying the Mitzvah at all. He quotes such great Acharonim as the Chayei Adam, Bet Ha’Levi, and Mishnah Berura as ruling accordingly.
One who has only two candles on the second night of Chanukah and knows that if he lights both now, he will not have anything to light the following night, one should only light one candle now and leave the other one for the following night. (Chazon Ovadia- ibid, page 29)