Are you asking what Homer says in Book 24? Or are you asking how to translate the line that the movie Troy has Brad Pitt say, which is taken out of context from Homer (for some reason they have Achilles deliver it at the end of a speech totally unrelated to its context in Homer, where Achilles says it to Priam as consolation)? I guess in any event it comes out to be the same thing. From what I can tell it's a rather poor translation (I believe it's Fagles' version?) of Iliad Book 24.525:

ὡς γὰρ ἐπεκλώσαντο θεοὶ δειλοῖσι βροτοῖσι/ζώειν ἀχνυμένοις: αὐτοὶ δέ τ᾽ ἀκηδέες εἰσί.

For thus the gods have spun fate for wretched mortals, to live grieving: but they themselves are carefree

Technically speaking the relevant phrase is only δειλοῖσι βροτοῖσι, but it really doesn't mean what Fagles wants it to mean. The phrase δειλοῖσι βροτοῖσι is in the dative with the verb ἐπικλώθω (to spin thread). Fagles switches around the sytnax pretty drastically to get it to say what he likes, and he also adds in quite a lot (Fagles wants the gods, for example, to be weaving sorrow into the lives of mortals, which is simply not what the Greek says at all, Homer's quite clear that it's mortals who are suffering, ἀχνυμένοις is a dative participle). My translation is maybe not as elegant, but it's much more literal, and shows that while one could translate Homer to get what Fagles has it's not really possible to translate backwards from Fagles to get Homer--and simply lifting the line from Homer doesn't give the sense that you're looking for, because that's not what Homer says