the masnavi or mathnawi,
The guidelines:
Couplet (or two-line) form…
…but with the qualifier that each “line” is actually a “half-line” and that they rhyme horizontally
Each line is 10 or 11 syllables long (I believe it’s supposed to be consistent within the poem, so pick a number and stick with it)
Rhyme scheme is aa/bb/cc/dd and so on
No line length restrictions
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Many examples of masnavi are very long poems. One of the more popular examples is Rumi’s Masnavi-ye-Ma’navi, which is a long spiritual or mystical poem.
Thankyou to the Writers Digest for this information.
Helpful Links
https://en.wikipedia.org/wiki/Mathnawi
https://www.writersdigest.com/write-better-poetry/masnavi-or-mathnawi-poetic-forms