Which fast days are obligatory by Torah or Rabbinic law?

Synopsis

Four fast days are obligatory: 9th of Av, 17th of Tammuz, 3rd of Tishrei (Fast of Gedaliah), and 10th of Tevet, all rooted in prophetic tradition via Zechariah.

Early Acharonim
Late Acharonim
Lenient
Strict
Lesser cited
Major authority

Discussion

Discussion coming soon.

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