A Comparative Study of 'Zahāf' (modification; substitution) meaning and application in Persian and Arabic Aruz (prosody)

"Zahāf" in  Arabic lexicon means 'to become remote from the origin; crawling of the child'. In Arabic prosodic terminology, 'zahāf' refers to poet's numerous options that make easy compose poems for Arab poets. In Persian poetry they are inevitable principles though are difficult to follow, make Persian poetry more harmonic. Arab poets compared to Persian poets have more options in using different forms of words. The present article by using documentary research, extracts zahāfs principles and their causes from different Arabic prosody books and compares them with Persian prosodic traditions. The comparison shows that Persian poets cannot follow Arabic prosody all the times. So, Persian prosodists explore new rules. However, Persian prosody is not so remote from Arabic prosody to make necessary completely new mechanism for Persian rhythm.