I appeal to you, brothers, by our Lord Jesus Christ and by the love of the Spirit, to strive together with me in your prayers to God on my behalf...
Romans 15:30 ESV

God isn’t a rock that can be moved merely by the application of greater force, but consider the Hebrews in Egypt. If one person prayed for rescue, he might have intervened for that person, but we would be unlikely to ever hear of it. If the Hebrews had prayed for the destruction of Egypt or for political power without leaving, he probably would not have responded at all. He might even have increased their oppression. However, when the whole nation cries out together for something that God very much wants to give them, he works great miracles that change the whole world.

God is pleased when his people are united and even more so when they are united in alignment with his will. There is power in the prayers of a single righteous man, but there is exponentially more power in the collective prayers of a righteous people.

This too is echoed by James when he wrote, "You ask, but you don't receive, because you ask wrongly."