Romans 4:5

But to the one who does not work, but believes in Him who
justifies the ungodly, his faith is credited as righteousness.
- New American Standard Bible

Psalm 127:1

Unless the LORD builds the house,
   the builders labor in vain.
Unless the LORD watches over the city,
   the guards stand watch in vain.

James 5:16

"Therefore confess your sins to each other and pray for each other so that you may be healed. The prayer of a righteous person is powerful and effective."
- New International Version (NIV)