Luke 4:25

But I tell you truly, there were many widows in Israel in the days of Elijah, when the heaven was shut up three years and six months, and there was a great famine throughout all the land;

Romans 10:9

because, if you confess with your mouth that Jesus is Lord and believe in your heart that God raised him from the dead, you will be saved.

Romans 15:9

and in order that the Gentiles might glorify God for his mercy. As it is written: "Therefore I will praise you among the Gentiles, and sing to your name";

Revelation 11:6

These have the power to shut up the sky, so that rain will not fall during the days of their prophesying; and they have power over the waters to turn them into blood, and to strike the earth with every plague, as often as they desire.

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 I tell you truly, there were many widows in Israel in the days of Elijah, when the heaven was shut up three years and six months, and there was a great famine throughout all the land;
Revelation 11:6
These have the power to shut up the sky, so that rain will not fall during the days of their prophesying; and they have power over the waters to turn them into blood, and to strike the earth with every plague, as often as they desire.

If they pray

Romans 10:9
because, if you confess with your mouth that Jesus is Lord and believe in your heart that God raised him from the dead, you will be saved.
Romans 15:9
and in order that the Gentiles might glorify God for his mercy. As it is written: "Therefore I will praise you among the Gentiles, and sing to your name";