At-Tabarī
The story of Haftvād appears in the "Book of the Deeds of Ardashir," a mythological tale written in the Sassanid period and used by Ferdowsi as a source in writing the "Shahnameh". A more abbreviated reference to the story exists in "History of the Prophets and Kings", a monumental work by the famous 9th-century Persian historian Muhammad ibn Jarir al-Tabari.