BTW, I have a sheila for the kollel. We were discussing the dinim of
havdallah and how when we make the bracha of "Borei M'orei Ha'aish" when we
are we near the flame, we let the light play off our nails.
However, not only do those near the flame do it, but even people at the back of the room
who clearly cannot utilize the flame. Is there a source for the people in "the bleachers"?
Be well,
Jay Gold
The custom to look at the fingernails by the light of the Havdalah flame is mentioned in such early sources as Pirkei d'Rebbi Eliezer, Rav Amram Ga'on, and the Zohar. The custom is cited by the Shulchan Aruch as well (OC 298:3).
As you assumed, the custom is based on the Mishnah in the eighth Perek of Berachos (51b) and the Gemara there (53b), which says that we may only recite a blessing over a flame at Havdalah if we are able to benefit from the light of that flame. The Gemara says that if one can differentiate between two types of coins, this is an example of benefiting from the light. By using the light to differentiate between our fingernails and the flesh around the nails, we are thereby using the light (TUR OC 298; see also Mishnah Berurah 298:9). Why fingernails? The Mishnah Berurah explains that fingernails, which are constantly growing and reproducing themselves, are symbolic of blessing and increase.
The DARCHEI MOSHE (OC 298:2) says that the customs of the Jewish people are like Torah (that is, they are not to be taken lightly), and he mentions that this particular custom has deep and "hidden signifance that is bound with the Heavenly chariot as is discussed at length in the Zohar, Parshas Vayakhel (208b)..." (the Mordechai, cited by the Beis Yosef, also mentions the custom of at one's fingernails to remember the nails of Adam ha'Rishon, as mentioned in Pirkei d'Rebbi Eliezer Ch. 14 and in the Zohar, see also Rashi on the Torah Bereishis 3:21).
The reason why people standing "in the bleachers" during Havdalah look at their nails is to see whether or not they can indeed benefit from the light of the flame, because if they cannot benefit from it, they have to move closer. (While it could be that there is something to looking at the fingernails on Motza'ei Shabbos, even without using the light of the Havdalah flame, based on the Zohar cited by the Mordechai and Darchei Moshe, nevertheless those people in the back who are too far away to utilize the flame have not fulfilled their obligation to recite a blessing over a flame Motza'ei Shabbos, and they should move closer and recite the blessing where they can benefit from the flame.)
I hope this information was helpful.
All the best,
Y. Shaw