Eliyahu himself said "is there no Elokim in Yisrael?!" Why did the messengers say that Hashem said so (verse 6), and so Eliyahu said (verse 16)?
Malbim (3, 6): Hashem did not command him to speak to the king, rather, to the messengers, and rebuke them for going. They feared to say that Eliyahu rebuked them for obeying the king's command. Therefore, they said that it was all part of the Nevu'ah.
Perhaps indeed, Hashem commanded to say also these words 1 . "V'Daber" is a command; it seems that He commanded to say the following words, for it does not say after this 'and Eliyahu said
Indeed, "Ko Amar Hashem" (verse 4) implies that Hashem did not say the previous words. However, perhaps "Ko Amar Hashem" introduces a decree, or distinguishes - you seek Ba'al Zevuv, but Hashem says
