Joel ben Samuel Sirkis (יואל סירקיש) also known as the Bach (ב"ח)—an abbreviation of his magnum opus, Bayit Chadash—was a prominent Jewish posek and halakhist. He lived in central Europe and held rabbinical positions in Belz, Brest-Litovsk and Kraków. He lived from 1561 to 1640.
Sirkis was born in Lublin in 1561. At age fourteen he went to the yeshiva of R. Naftali Zvi Hirsch Schor, a leading student of R. Moses Isserles. After remaining there some time he went to Brest-Litovsk, where he attended the yeshiva of Rabbi Phoebus. While still a youth he was invited to the rabbinate of Pruzhany, near Slonim. Later he occupied the rabbinates of Lukow, Lublin, Medzyboz, Belz, Szydlowka, and finally Brest-Litovsk and Kraków, succeeding in each of the two last-mentioned places his teacher R. Phoebus.
"The Bach" was an adherent of the Kabbalah and an opponent of pilpul. He was also critical of those who relied solely on the Shulchan Aruch for halachic decisions, rather than on the Talmud and the Geonim. He was the father-in-law of Rabbi David HaLevi Segal, who frequently refers to him in Turei Zahav, his commentary on the Shulchan Aruch. Rabbi Sirkis died in Kraków in 1640.
- Bayit Chadash (בית חדש - "New House", a reference to Deuteronomy 22:8, abbreviated as Bach - ב"ח), Rabbi Sirkis's best known work, is a major commentary on the Arba'ah Turim of Jacob ben Asher. The work presents and elucidates the fundamental principles of the Torah as recorded in the Mishnah, the Babylonian and Jerusalem Talmuds, and the chief codes.
- Hagahot haBach (glosses of the Bach) - suggestions for textual emendations in the Talmud and Rashi, copied from the notes that the author added to his copy of the Talmud. The Bach's notes are marked in the text as a letter in Rashi script within parentheses.
- Meshiv Nefesh, a commentary on the Book of Ruth, (Lublin, 1616).
- Teshuvot ha-Bach ("Responsa of the Bach").
- Beurei ha-Bach le-Pardes Rimmonim, explanations of passages in the Kabbalistic magnum opus of Moses ben Jacob Cordovero.