SIYYUM (Heb. סִיּוּם; "conclusion"), designation for celebrations held on certain occasions.
(1) Siyyum *Sefer Torah is a consecration ceremony held at the conclusion of the writing of a new Torah Scroll. The last, and sometimes the first, verses of the Torah are written by members of the congregation (each congregant filling in one letter); the scroll is then solemnly sanctified with special prayers and songs. The celebration is based on R. *Eliezer's interpretation of i Kings 3:15 (Song R. 1:1 no. 9).
(2) Siyyum Massekhet or Siyyum ha-Shas is the celebration held at the conclusion of the study of a Talmud tractate or of the whole Talmud. On this occasion the members of the study group recite special formulas of appreciation called הַדְרָן (hadran), in which they give thanks for having had the privilege of studying Torah; they petition for the opportunity to be able "to return again" to the study of this tractate. The hadran is chosen from rabbinic sources in the Talmud (Ber. 16b–17b) and is usually printed at the end of each tractate. On the occasion, a festive banquet is held (see *Se'udah) at which the lecturer delivers a discourse on his novellae to the Talmud tractate that has just been completed (also commonly known as hadran). The custom of the festive banquet dates back to talmudic times (Shab. 118b–119a), and it is a mitzvah to participate. Study groups often plan, if possible, to complete a Talmud tractate on the day before Passover to allow the firstborn male to dispense with fasting on this day; partaking of the siyyum meal overrides the fast. (See *Fasting and Fast Days.)
(3) In North African Jewish communities, especially in Algeria, a siyyum, called Ḥag Siyyum or Se'udat Yitro u-Moshe, was yearly celebrated on the Thursday before the Sabbath on which the Torah portion Yitro (Ex. 18–20) was read in the synagogue. At the celebration (based on Ex. 18:12) the *Ten Commandments were solemnly read to the congregation and a festive banquet held at which chicken was served.
Eisenstein, Dinim, 288–9.