A timely acquisition. This week I received the first known edition of the Tikun Leil Shavuot, printed in Venice in 1648.
The introduction states: “It’s a sacred Jewish custom to study on the nights of Shavuot and Hoshana Rabba; to read from Torah, Nevi’im, Mishnah and Talmud, Aggadah and Kabbalistic books…and although there are many customs, almost all are like those of the two great luminaries, the Rama”k and the Ar”i.”
While no mention is made in the Shulchan Aruch of the custom to stay awake on Shavuot night and recite Tikun Leil Shavuot, within a few decades of the Shulchan Aruch’s publication, we have numerous references to this practice throughout the Jewish world.
The first mention appears in the commentary of the Magen Avraham (ca. 1671) on Shulchan Aruch: “The Zohar states that the early chassidim stayed up all night [on Shavuot] and studied Torah. It has already become the custom of most learned Jews. There is also a more straightforward reason for this custom: The Jews slept through the morning of the receiving of the Torah, and Hashem was forced to awaken them, as stated in the Midrash; therefore, we need to rectify this [deed by staying awake].”
We have records of R. Yosef Karo observing this custom despite there being no mention of it in the Shulchan Aruch. The Shelah (died 1630) quotes a letter written by R. Shlomo Alkabetz that describes R. Yosef Karo and his companions observing this custom on Shavuot.
Chemdat Yamim, an anonymous work written in the late 17th-early 18th century, also talks of the custom being prevalent: “It has already become a widespread practice in all of the diaspora to avoid sleep and sanctify oneself on this night.”