Sayid stabs Locke/smokey, Locke offers Sayid what he wants

In the jungle, Sayid stops for a drink of water and hears the signature sounds of the smoke monster. Locke appears behind him and says "Hello Sayid." Sayid quickly shoves the dagger into Locke's chest. There is no blood and Locke is unaffected. Locke pulls the dagger out and offers it back to Sayid.

Locke says that Dogen knew that Sayid wouldn't be able to kill him, so he really sent Sayid out there so Locke would kill him. Locke asks Sayid if he'll deliver a message for him in exchange for the one thing he wants in the world, which Sayid says died in his arms (presumably this is Nadia). Locke says that he could see her again.

So who lied, Dogen or Locke or both? Would Sayid have been able to kill Locke if Sayid hadn't let him speak first? Can and will Locke deliver on his promise to give Sayid what he wants?