Rashnu is the Avestan language name of the Zoroastrian yazata

Yazata

Yazata is the Avestan language word for a Zoroastrian concept. The word has a wide range of meanings but generally signifies a divinity...

of justice. Together with Mithra

Mithra

Mithra is the Zoroastrian divinity of covenant and oath. In addition to being the divinity of contracts, Mithra is also a judicial figure, an all-seeing protector of Truth, and the guardian of cattle, the harvest and of The Waters....

 and Sraosha

Sraosha

Sraosha is the Avestan language name of the Zoroastrian divinity of "Obedience" or "Observance", which is also the literal meaning of her name....

, Rashnu is one of the three judges who pass judgment on the souls of people after death. Rashnu's standard appellation is "the very straight."

In creation accounts

In the Bundahishn

Bundahishn

Bundahishn, meaning "Primal Creation", is the name traditionally given to an encyclopædiaic collections of Zoroastrian cosmogony and cosmology written in Book Pahlavi. The original name of the work is not known....

, 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

Amesha Spenta

' is an Avestan language term for a class of divine entities in Zoroastrianism, and literally means "Bounteous Immortal" The noun is amesha "immortal", and spenta "furthering, strengthening, bounteous, holy" is an adjective of it...

 Ameretat (Amurdad), "immortality". (GBd xxvi.115). In a subsequent passage, Rashnu is described as the essence of truth (arta/asha

Asha

Asha is the Avestan language term for a concept of cardinal importance to Zoroastrian theology and doctrine. In the moral sphere, aša/arta represents what has been called "the decisive confessional concept of Zoroastrianism." ...

) that prevents the daevas

Daeva

Daeva in Avestan language meaning "a being of shining light", is a term for a particular sort of supernatural entity with disagreeable characteristics. Equivalents in Iranian languages include Pashto dêw , Baluchi dêw , Persian dīv , Kurdish dêw...

 from destroying material Creation

Ahura Mazda

Ahura Mazdā is the Avestan name for a divinity of the Old Iranian religion who was proclaimed the uncreated God by Zoroaster, the founder of Zoroastrianism...

. "Rashnu adjudges even the souls of men and women as to bad deeds and good deeds. As one says, 'Rashnu shall not see thither the rank of the judge who delivers false judgment.'" (GBd xxvi.116-117).

In other texts

In the Avestan Dahman Afrin

Dahm

Dahman or Dahman Afrin is the Avestan language name of a Zoroastrian concept, later considered to be the embodiment of prayer, and ultimately as a divinity, one of the yazatas....

, Rashnu is invoked in an address to Ameretat. According to the Denkard

Denkard

The Dēnkard or Dēnkart is a 10th century compendium of the Mazdaen Zoroastrian beliefs and customs. The Denkard is to a great extent an "Encyclopedia of Mazdaism" and is a most valuable source of information on the religion...

, the Duwasrud Nask - a legal manual now lost - contained passages extolling the supremacy of Rashnu. (Dk 8.16) In the Siroza ("thirty days") "the very straight Rashnu ... augments the world and is the true-spoken speech that furthers the world." (Siroza 18).

Holy days

The 18th day of every month in the Zoroastrian calendar

Zoroastrian calendar

This article treats of the reckoning of days, months and years in the calendar used by adherents of the Zoroastrian faith. Zoroastrian religious festivals are discussed elsewhere, but have a fixed relationship to Nawruz, the New Year festival, whose timing is discussed below...

is dedicated to Rashnu. The Counsels of Adarbad Mahraspandan, a Sassanid-era text, notes that on the 18th day "life is merry".