A Lack of Emunah Blocks the Heavenly Pipeline:
The Lechovitcher Rebbe zy”a (Sefer Toras Avos) quotes the Rebbe Rav Zushe zy”a as saying that he heard the following explanation from Eliyahu Hanavi. (It is also cited in Sefer Noam Elimelech in the name of Rav Zusha).
Why are the pesukim in a question and answer format. Why does it say: If you will ask what you will eat, the answer is that Hashem will send His blessings. Why doesn’t it just say that Hashem will send his blessings without the need for the question?
The answers is that the nature of the world is that everyone is provided with as much as he needs. But if someone lacks bitachon in Hashem, the pipeline of goodness is blocked for him and he stops receiving his full share of sustenance. In this case, if the people are asking what they will eat, they are causing their pipes to be blocked. Therefore, Hashem specifically guarantees that even people whose bitachon is lacking and who ask such a question will be provided with a new pipelines for Hashem to send His blessing, and they will receive enough produce during the sixth year to last for three years. But if one doesn’t even ask and simply trusts in Hashem to provide for him, he does not need these new pipelines. They will receive their usual sustenance without the need for any new guarantees.