In Mandaean cosmology, Piriawis (Classical Mandaic: ࡐࡉࡓࡉࡀࡅࡉࡎ; sometimes also spelled Biriawiš ࡁࡉࡓࡉࡀࡅࡉࡔ[1]), also known as the Yardna Rabba (ࡉࡀࡓࡃࡍࡀ ࡓࡁࡀ "Great Jordan"), is the sacred life-giving river (yardna) of the World of Light.
It is the heavenly counterpart of rivers on Earth (Tibil), which are considered by Mandaeans to be manifestations of the heavenly Piriawis.
[2][3][4] Shilmai and Nidbai are the two guardian uthras (celestial beings) watching over Piriawis.
[2] Qulasta prayers 13 and 17 mention Piriawis-Ziwa and Piriafil-Malaka together as uthras.
[5] In Book 4 of the Right Ginza, Sindiriawis is mentioned as "the great yardna of the Life" (sindiriauis, iardna rba ḏ-hiia).