The Gemara (Shabbos 23:) states, הויין בנר הרגיל חכמים תלמידי בנים ליה, “A person who is cautious with lighting the candles [of Shabbos and Chanukah – Rashi] will merit children who are talmidei chachamim, as it states, מצוה נר כי אור ותורה.”
This is a wonderful promise, but the question that is asked by the Rishonim is, do we see it happening? Do we see people who are cautious with Shabbos lecht and Chanukah lecht having children talmidei chachamim?
Rabbeinu Yitzchak, the son of the Raavad, asks, "Why isn't everyone a talmid chacham? Most people are cautious with Chanukah lecht, so why don’t we see that everyone merits to be talmidei chachamim?!"
He answers, "Few people keep this mitzvah with all its details and halachos."
There might be another answer. When the Meiri discusses the segulah of lighting Chanukah lecht to merit children talmidei chachamim, he writes, מצוה חיבוב דרך בנר הרגיל חכמים תלמידי בנים לו הוין מפורסמת והערה, "Whoever is cautious with the candles to light them with love for the mitzvah and with visible excitement, will be granted children talmidei chachamim." It isn't sufficient to just light the Shabbos and Chanukah lecht. It must come with a love and excitement for the mitzvah, and then he will merit children talmidei chachamim.
One year, on Chanukah, Reb Chaim Ozer Grodzinski zt'l was in Crakow. He came to a tailor’s home and asked the tailor to fix his jacket. "I haven’t lit Chanukah lecht yet," the tailor replied.
"I'll wait," Reb Chaim Ozer replied. He thought it would be just a few moments. How long does it take to light Chanukah lecht?
It took much longer than a few moments. Reb Chaim Ozer watched in astonishment and admiration as the tailor, dressed in his Shabbos clothing, sang songs for a half hour near the lecht, with obvious happiness for the mitzvah.
Reb Chaim Ozer said, "Now I understand why Crakow produced so many great talmidei chachamim over the generations." It is because the mitzvah of Chanukah lecht is mesugal for children talmidei chachamim, especially when performed with love and passion.
Chazal say that for being cautious with Chanukah lecht, one merits children talmidei chachamim.
The Chidushei HaRim zt'l adds that the one who lights the candles will also become a talmid chacham. If it is mesugal for his children to become talmidei chachamim, it is certainly mesugal that the person who lights the lecht will become a talmid chacham. Furthermore, tzaddikim say that if chas veshalom one has a child who strayed from the derech, the parent's mitzvah of Chanukah lecht can bring him back.
A woman approached the Yesod HaAvodah (Slonim) zt'l while he was walking down the street with his gabbai and told the Rebbe that her daughter had strayed off the path and had run away from home.
The Yesod HaAvodah asked, "Do you have clothing that belongs to your daughter?" She said that she does.
"Turn the garment into wicks and use them to light the Shabbos lecht."
She did so.
The segulah worked. That Friday night, the girl returned home. The family was then in the middle of their Shabbos seudah, and they were overjoyed to see her. She said, "I regret running away. I acted foolishly. I want to return home and to Yiddishkeit."
The Beis Avraham zt'l repeated this story and added that this is implied in the brachos, שבת של נר להדליק. The correct translation of להדליק isn't “to light.” It means “to ignite.” The Shabbos lecht ignites the neshamah of a Yid.
The Beis Avraham adds that on Chanukah, we say חנוכה נר להדליק because Chanukah lecht ignites the neshamah, the hearts of the Jewish nation, to draw them to teshuvah.
