tasliim : 'Delivering, consigning; committing to the care of; surrender, resignation; conceding, acknowledging, granting; assenting to, accepting'. (Platts p.324)
He says, it is far from the rank of passion that he would consider labor to be the means of his success. That is, Farhad cut through the Pillarless Mountain so that a pleasure-house for Khusrau could be made from that stone. This was the task of a laborer. The glory of passion is much more lofty and exalted than this. For this reason, we have doubts about the good reputation of Farhad. We cannot enter his name in the list of lovers. (157-58)
Having become a lover, how fine it was to labor to build a pleasure-house for his Rival, Khusrau! We have doubts about Farhad's good reputation and esteem. That is, a person with proper pride cannot possibly perform labor when the beloved lives with the Rival. (207)
He was given the order to cut a channel through the mountain, for Shirin's garden, and he was promised that upon completing the channel, Shirin would be his. Farhad completed the channel, but when he was given false news of Shirin's death, he was obliged to kill himself. This is the common story; it has no relation to history.... Mirza [Ghalib] has brought out a point in the story of Farhad that certainly cannot be considered to his credit.... If it is said that Farhad had set out to dig a channel for Shirin, then Shirin was the wife of Khusrau Parvez; the channel that was made for her palace and garden, was in any case for the pleasure-house of Khusrau Parvez himself. (344)
The story of Shirin and Farhad is told in various versions; see {1,2} for further discussion.
This verse is another in the series of snide remarks about famous lovers of the past; for more about such verses, see {100,4}.
The chief charm of the verse is surely its shock value. As Mihr observes, Ghalib has brought out a new and unexpected aspect of a traditional story-- and has insulted, with a show of virtuous indignation, one of the great lovers of ghazal tradition. He's done a similar thing already in {3,6}, in which he sneers at Farhad for needing to use an axe to kill himself.
All such snide remarks can of course also be taken as tongue-in-cheek. The later lover might well be jealous of his predecessor's fame, and could thus be reacting with a sour-grapes attitude. He might well jump at the chance to do, himself, what he accuses Farhad of doing. (In this connection, consider {99,3}.) For after all, isn't the beloved properly worth any sacrifice-- including the sacrifice of pride, and self-respect, and one's good name?
Note for grammar fans: Nazm's criticism is that 'by us X is [not] accepted/granted' is what the grammar needs to be, just as in the case of man:zuur . But this isn't the sense of tasliim , which means 'accepting, granting'. Nazm's objection assumes that there is no i.zaafat after tasliim ; if there were one, then the grammar would work well: 'by us is [not] the accepting/granting of X'. Of course, the i.zaafat is a Persian construction, and in principle it should not be used with Arabic words. Perhaps that's why Arshi gives no i.zaafat ; as usual, I follow his text. (However, in {169,3}, Ghalib has clearly used tasliim-e hosh .)
Nazm:
[He criticizes the verse for a misuse of Arabic grammar: tasliim should mean actively 'accepting, granting', rather than 'accepted, granted'.] (107)
== Nazm page 107