Joel 1

In the first chapter of Joel we have described a formula for effective prayer …

Put on sackcloth, you priests, and mourn;
    wail, you who minister before the altar.
Come, spend the night in sackcloth,
    you who minister before my God;
for the grain offerings and drink offerings
    are withheld from the house of your God.
Declare a holy fast;
    call a sacred assembly.
Summon the elders
    and all who live in the land
to the house of the Lord your God,
    and cry out to the Lord.

I must say, this would be a rare event