Yahweh speaks of himself by name to express the certainty of what he is declaring. See how you translated this in [Jeremiah 1:8](../01/07.md). AT: "this is what Yahweh has declared" or "this is what I, Yahweh, have declared" (See: [[rc://en/ta/man/translate/figs-123person]])
The phrase "in my name" represents speaking with Yahweh's power and authority or as his representative. Here these prophets claim that they received their message from Yahweh, but that had not. The abstract noun "deceit" can be translated as the verb "deceiving." AT: "they say they are speaking for me when they prophesy, but they are deceiving you" (See: [[rc://en/ta/man/translate/figs-metonymy]] and [[rc://en/ta/man/translate/figs-abstractnouns]])