In Arabic "rubai'i" refers to a type of 4-line verse, & this is a book of them, like Omar Khayyam's
He rejected the idea of translating Bulleh Shah in free verse after initial ... in 
whose translation of Omar Khayyam, no source of fifth rubai could be ... if a 
translator could insert an entire apocryphal rubai, I was certainly ... like to use the 
word 'rendering' instead of translation for his work as .... Books & Authors.