Together with Mithra and Sraosha, Rashnu is one of the three judges who pass judgment on the souls of people after death.
In the Bundahishn, a Zoroastrian account of creation finished in the 11th or 12th century, Rashnu (Middle Persian: Rashn) is identified as an assistant of the Amesha Spenta Ameretat (Amurdad), "immortality".
In a subsequent passage, Rashnu is described as the essence of truth (arta/asha) that prevents the daevas from destroying material Creation.
According to the Denkard, the Duwasrud Nask - a legal manual now lost - contained passages extolling the supremacy of Rashnu.
The Counsels of Adarbad Mahraspandan, a Sassanid-era text, notes that on the 18th day "life is merry".