Wikipedia
The Masnavi, or Masnavi-I Ma'navi , also written Mathnawi, Ma'navi, or Mathnavi, is an extensive poem written in Persian by Jalal al-Din Muhammad Balkhi also known as Rumi, the celebrated Persian Sufi saint and poet. It is one of the best known and most influential works of both Sufism and Farsi Dari literature. The Masnavi is a series of six books of poetry that together amount to around 25,000 verses or 50,000 lines. It is a spiritual writing that teaches Sufis how to reach their goal of being in true love with God.
Masnavi, or mathnawī, is the name of a poem written in rhyming couplets, or more specifically, "a poem based on independent, internally rhyming lines". Most mathnawī followed a meter of eleven, or occasionally ten, syllables, but had no limit in their length. The mathnawi consists of an indefinite number of couplets, with the rhyme scheme aa/bb/cc.
Mathnawī have been written in Persian, Arabic, Turkish, Kurdish and Urdu cultures.