Piriawis

In Mandaean cosmology, Piriawis (sometimes also spelled Biriawiš ࡁࡉࡓࡉࡀࡅࡉࡔ ), 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.

Shilmai and Nidbai are the two guardian uthras (celestial beings) watching over Piriawis.

Qolasta prayers 13 and 17 mention Piriawis-Ziwa and Piriafil-Malaka together as uthras.

Other names
In Book 4 of the Right Ginza, Sindiriawis is mentioned as "the great yardna of the Life" (sindiriauis, iardna rba ḏ-hiia).