The heart in this poem is not a metaphor for the man. It is something he lives alongside and cannot control, like a lodger who keeps bringing trouble home. By the last couplet he is in a crowded room and the heart is leaving it with somebody else. He does not chase it. He swears an oath on the smile that caused it, and that is the entire response.
Urdu makes that possible in a way English cannot copy. Dil ka means of the heart, and in Urdu it lands right at the end of the line. So every line runs its course, describes something happening, and only in its final breath tells you who it happened to. Thirteen times the poem names an action and then hands it over to somebody else. The man is the heart's landlord at best.
It matters who wrote this, and it settles nothing. Naseeruddin Naseer ran a shrine. He was a religious figure with a following, writing a poem full of smiles, wrists, gatherings and a beloved who will not listen. In this tradition that is no contradiction, and it is not a code to be cracked either. The beloved has always been readable as a person or as God, and a good poet keeps both alive rather than choosing between them.
The couplet about the mark on the water is where it presses hardest. Not a line on water, he says, not something imagined, not a dream, so why treat wiping out a heart as a game? Read one way, he is telling a careless lover that what he feels is real. Read another way, he is telling all of us that the soul is.
It travelled the way most of this poetry travels now, through qawwali. Nusrat Fateh Ali Khan's recording is where most people first hear it, and like most sung versions it takes a selection of the couplets rather than all thirteen, in whatever order suits the singing.
How it rhymes
Every second line closes on the same word — دل کا
, dil ka. That repetition is the radif.
The rhyme falling just before it is the qafiya: The -ana sound just before the refrain: aana, zamana, fasana, jana, purana, samana, lagana, thikana, satana, milana, mitana, khazana.
Hearing the two land together at the close of every sher is most of what makes this form sound the
way it does.