The founder of the Chassidic movement, Rabbi Yisroel ben Eliezer, the Baal Shem Tov, shares the same Yahrtzeit as King David — the second day of Shavuos. Both men are tied to the concept of Messianic arrival. King David is the first in the Davidic line from which will eventually produce and bring Moshiach, who will be king thereafter. And the Baal Shem Tov once asked Moshiach in Heaven when he would come down. Moshiach answered, “When your teachings will spread to the whole world.”
On Erev Shavuos, the Baal Shem Tov prepared for his own death. He finalized his will, ensuring his legacy. He bequeathed most of his seforim, his holy books, to one of his students who would take on the mantle of leadership after the Baal Shem Tov. However, any sefer that was in Yiddish he left to his daughter Adel.
The way he settled his affairs mirrors another aspect of Shavuos. Here’s how: We are told that when the Jewish nation accepted the Torah, the melachim, the angels, protested: they didn’t think the Torah should be given to beings of flesh and blood. Arguments went back and forth how to ensure that these mere mortals would not bring shame to the Torah. Even the merit of our illustrious ancestors was not enough of a guarantee for the melachim. However, when the Jewish women said that they would guarantee their children would learn Torah, the melachim acquiesced. The revelation at Mount Sinai was given. That is why the Torah says (Shemos 19:3), “Koh Somar l’Bais Yaakov,” “So shall you say to the House of Yaakov.” Moshe was instructed to teach the women first (“House” refers to the women). In his will, the Baal Shem Tov also made sure to single out a woman as a recipient of his tradition. He left a legacy of learning to his daughter, not only to his male students.
It is interesting to note that the Baal Shem Tov stipulated that the holy books in Yiddish be given to his daughter. Perhaps that is why Chassidic girls’ schools do all their teaching of Torah in Yiddish to this day.