S. R. Faruqi:

Usually they say āfat kā parkālah [spark of disaster], but with regard to the affinity, he said āg kā parkālah [spark of fire]. The meaning of garmī chashm rakkhe is garmī kī ummīd rakkhe , with the kī omitted. The omission of the izafat [iẓāfat kā ḥazaf] is common in Persian and abnormal in Urdu. But in Ghalib and Mir, there are examples of it.

[See also {352,7}.]

FWP:

SETS == IDIOMS
MOTIFS == EYES
NAMES
TERMS == IZAFAT

The eye imagery of intiz̤ār karnā ('to wait', based on 'to look out for') is here echoed in the sense of kī chashm rakhnā , 'to keep an eye out for'; SRF ascribes to it an overtone of hopeful, rather than merely neutral, waiting. Someone may 'keep an eye out' in hope for heat from that spark of fire, only when he would set fire to his whole body and mind, as I have done. That 'spark of fire' may be the mischievous beloved, who is the 'spark of disaster' [āfat kā parkālah] of the usual idiom (here enjoyably altered); or perhaps a kind of metaphorical, late-stage fire of passion like that envisioned in

{15,3}.

In either case, the verse turns on the pivot of tab , which is perfectly positioned to mean 'then', and of course also means 'heat', as in

{15,1}.

Why merī t̤araḥ se ? If it's taken merely to mean 'as I have done', then it adds nothing to the verse and almost looks like padding. But if we take it more seriously, then the verse claims that it's necessary not just to burn up one's whole body and mind, but to do it in one particular way, 'in my style/manner'. Of course, it's left to us to decide what this style/manner might be.

Note for meter fans: It's necessary to read rakkhe , with a tashdīd , to make the line scan; this kind of optional doubling in the perfect is relatively common. Also, notice that t̤arḥ can also be scanned as t̤araḥ ; this scansion is in fact very common.