What is the nature of the four fasts in terms of biblical versus rabbinic obligation?

Synopsis

The four fasts derive from prophetic tradition (Zechariah 8:19) and are obligations established by the Sages based on historical tragedies, representing a balance between communal need and not overburdening the people.

Rishonim
Late Acharonim
Lenient
Strict
Lesser cited
Major authority

Discussion

Discussion coming soon.

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