Which interpretation of “the salty spring” is most precise?

Narrator Criticism: Corruption, Concealed Sources and Chronological Testing

• It is an individual, evidence-based ruling on each of Mahdī’s texts
• It is a literal report about the meeting-place and its water
• Ḥammād’s figurative adverse judgment of the gathering
• It is an acknowledgment of hearing that necessarily accredits Mahdī