Due to the rejoicing of Rashbi, we do not even permit the recital of nacheim [a prayer lamenting the destruction of the Beis HaMikdash and pleading for its restoration; normally reserved for Av 9]. Although nacheim is a prayer and request to terminate our exile [and therefore has a positive side], nevertheless, it emphasizes the opposite of happiness [by mentioning the destruction and consequent exile].
The scholar who died for reciting nacheim
Indeed, there is a story of one [exceptional scholar] who [had the unique custom of reciting nacheim daily, throughout the year. However, when he] recited nacheim on Lag B'omer, he was penalized [from Heaven] with a most harsh punishment – the opposite of prolonged life... (Parshas Acharei-Kedoshim, Iyar 13 5748; Hisvaaduyos p. 297)
Despite the fact that it was this person's custom to recite Nacheim every day of the year. (Parshas Emor, fn. 97; Hisvaaduyos p. 169) [Seemingly, his action should not have been perceived as "slighting" Rashbi's Yom Hilula by dampening the joy with the sadness of exile; after all, this scholar even recited nacheim on Shabbos and Yom Tov, and was not punished for dampening even such Biblically mandated joy!]
Why such a harsh punishment?
Two unique points [that beg explanation] emerge from the above story: 1) The actual punishment [i.e., the fact that Rashbi's dissatisfaction should result in the scholar passing away] is something totally and utterly irregular for tzadikim … 2) The fact that the punishment not only occurred, but was even publicized – despite the extreme caution normally exhibited to avoid publicizing an undesirable matter even concerning an animal [is highly abnormal].
However, the reasoning behind this story can be explained as follows: The extreme punishment occurred and was even publicized in order to greatly emphasize the tremendous importance of rejoicing on Lag B'omer – and to severely negate the opposite approach [i.e., dwelling on gloomy matters. The case of this scholar, then, served as a one-time demonstration of Lag B'omer's extreme spiritual importance. Perhaps the fact that many generations since, who now appreciate the importance of rejoicing on Lag B'omer, is retroactively credited to this scholar's serving as an (extreme) example – Ed].
Day of redemption
On the Rashbi's exalted level, the inner secrets of the Torah were openly revealed; as a result, the entire concept of the churban [destruction of the Beis Hamikdash and the subsequent exile] was completely non-existent for him. It is for that reason that on his Yom Hilula (i.e., the day of his passing, when his entire divine service was perfected and completed), the recital of nacheim is utterly negated. Quite the opposite – on this day, the Redemption is greatly emphasized! (Ibid., 5751, pp. 211-222)
