I am reading James Scully's translation of Philoktetes (also known as Philoctetes), in The Complete Plays of Sophocles, translated by Robert Bagg & James Scully. At one point, after getting Herakles' bow, Odysseus declares that he's leaving without Philoktetes:
(to the Sailors holding PHILOKTETES)
Yes! Let him go! Don't touch him. Let him
stay here. We've got your bow, we don't need you.
We have Teukros, an expert archer.
And me. I can handle the bow as well as you
and damn well aim it, too. Who needs you?
He then does leave, Neoptolemos and the bow in tow. But the prophecy clearly states that Philoktetes himself is required:
Whatever they asked, Helenos had
a prophecy for. He said they'd never sack Troy
with its towers—unless they could persuade
this man to leave this island here and
bring him back.
Or, since that is the "MERCHANT" sent by Odysseus, here from the introduction to the play:
they've learned they can't take Troy without Philoktetes
And throughout the play Odysseus tries his darndest to fulfil the prophecy. He's already collected Neoptolemos (that's the easy part) and now is sending the boy to collect the bow (also in the prophecy). Why, then, is he so willing to settle for two out of three of the requirements for victory? Why does he willingly leave Philoktetes behind?