Ghazal 24, Verse 7

Nazm:

That is, every sarcastic mouth is a link in the chain of disgrace. In the first line, 'is' is omitted. And they call the mouths of beautiful ones 'nonexistent'. So when the mention of your faithlessness is in their mouths, it's as if it has arrived at 'nonexistence', and on the feet of your good name the chains of disgrace have been fastened. (26)

== Nazm page 25; Nazm page 26

Hasrat:

The device [tarkiiib] of the 'chain-link of disgrace' is extremely farfetched. (25)

Bekhud Mohani:

Whether it be Janab [Nazm] Tabataba'i or Janab Hasrat or Shaukat, they all make of the circles of the mouths of beautiful ones, a chain of disgrace. It doesn't even occur to any of them that usually sarcastic people, while making sarcastic remarks about someone, go on smiling. If the venerable commentators had turned their attention this way, then during a smile, the curl [shikan] of the lips presents the image of a chain. Mirza says 'the mouth of every idol'. He doesn't say 'the mouths of idols' [as in a linked chain]. So how can this meaning exist? (61)

FWP:

SETS == DISRUPTION
EXISTENCE/NONEXISTENCE: {5,3}
IDOL: {8,1}
SPEAKING: {14,4}

Bekhud Mohani to the contrary, Nazm and the commentarial consensus surely provide a richer meaning. A mouth is round like a link in a chain; a mouth is also widely open and round to express surprise, (assumed) shock, or the relish of a scandal; or often simply in the course of emphatic conversation. After all, these are 'slander-seeking' idols. And gossip proceeds from mouth to ear to mouth, in an unbroken chain.

We are expecting the chain of their round, linked, scandal-bearing mouths to continue 'till Doomsday', or something of the sort; so that ((adam tak , 'till nonexistence', comes as a piquant pleasure, something that demands attention. (Perhaps the chain continues until the mouths become so small they're unable to speak?) Ghalib is playing with a conventional rhetorical trope: evoking it, and then thwarting or complicating it. For more on this trick of his see {21,10}.

In the ghazal world, a small mouth is a sign of beauty; and hyperbole is a poetic flourish, a sign of free-wheeling ingenuity. The beloved accordingly has a mouth vanishingly small, a mouth that really almost doesn't exist at all. (For more on this striking fact, see {91,4}.)

The implication seems to be that the beloved's ill-fame is passed along as gossip among various beloveds' tiny mouths until it pervades the whole realm of existence and even reaches beyond it into the realm of 'nonexistence'. And that's not a gradual process destined to occur over time, with a culmination at some future point: the 'is' brings it right into the present. Even as we speak, the lover tells the beloved, many small (virtually nonexistent) round mouths are eagerly gossiping about her disgraceful faithlessness in all the worlds-- not only in the world of existence, but in the world of nonexistence as well.