Luke 4:25

But of a truth I say to you, there were many widows in Israel in the days of Elijah, when the heaven was shut up three years and six months, when there came a great famine upon all the land;

Romans 10:9

that if you shall confess with your mouth Jesus as Lord, and shall believe in your heart that God raised Him from the dead, you shall be saved;

Romans 15:9

and that the gentiles might glorify God for His mercy; as it has been written, "For this cause, I will confess to Thee among the gentiles; and to Thy name will I sing praise."

Revelation 11:6

These have authority to shut the heaven, that it rain not in the days of their prophecy; and they have authority over the waters, to turn them into blood, and to smite the earth with every plague, as often as they may wish.

Treasury of Scripture Knowledge

Summary

When heaven is shut up, and there is no rain, because they have sinned against thee; if they pray toward this place, and confess thy name, and turn from their sin, when thou afflictest them:

If they pray

Bible References

Heaven

Luke 4:25
But of a truth I say to you, there were many widows in Israel in the days of Elijah, when the heaven was shut up three years and six months, when there came a great famine upon all the land;
Revelation 11:6
These have authority to shut the heaven, that it rain not in the days of their prophecy; and they have authority over the waters, to turn them into blood, and to smite the earth with every plague, as often as they may wish.

If they pray

Romans 10:9
that if you shall confess with your mouth Jesus as Lord, and shall believe in your heart that God raised Him from the dead, you shall be saved;
Romans 15:9
and that the gentiles might glorify God for His mercy; as it has been written, "For this cause, I will confess to Thee among the gentiles; and to Thy name will I sing praise."