Reb Mordechai of Lechovich says that the following Divrei Torah was heard by the Rebbe Reb Zisha of Anipoli, directly from Eliyahu HaNavi. The Noam Elimelech writes in the name of his brother, the Rebbe, Reb Zisha the following:
In Parshas Behar (25, 20-21) it says וְכִי תֹאמְרוּ מַה-נֹּאכַל בַּשָּׁנָה הַשְּׁבִיעִת הֵן לֹא נִזְרָע וְלֹא נֶאֱסֹף אֶת-תְּבוּאָתֵנוּ. - And if you will say: 'What shall we eat the seventh year? behold, we will not sow, nor gather in our crops'. וְצִוִּיתִי אֶת-בִּרְכָתִי לָכֶם בַּשָּׁנָה הַשִּׁשִּׁית וְעָשָׂת אֶת-הַתְּבוּאָה לִשְׁלֹשׁ הַשָּׁנִים. Then I will command My blessing upon you in the sixth year, and it shall bring crops sufficient for the three years.
What need was there for the posuk to say: "And if you will say: What shall we eat the seventh year?" If the Torah would just write the next posuk: "I will command My blessing....", wouldn’t that be enough? Then we wouldn’t have to ask: "What shall we eat…"
These pesukim teach us how Hashem sends blessing down to this world. There is a constant abundant flow of blessings (shefa) that Hashem sends down to us, through pipes. As long as we have proper bitachon in Hashem the flow of shefa continues, unabated. If, however, the bitachon is lacking, then the shefa gets disturbed and Hashem has to send down a new flow of shefa. Therefore, one should always have bitachon that Hashem will provide; otherwise he is going to cause the flow of shefa to be interrupted.
This is all seen in those pesukim. If one shows he doesn’t have bitachon by asking: "What shall we eat the seventh year?", then the shefa gets interrupted, causing Hashem to say: "I will command My blessing…"; He will now have to send down a new flow of shefa.
May we all be zoche to have proper bitachon in Hashem, with an uninterrupted flow of shefa showering down on us.