Luke 18:1, 6-8

And he spake a parable unto them to the end that they ought always to pray, and not to faint

And the Lord said, Hear what the unrighteous judge saith. And shall not God avenge his elect, that cry to him day and night, and yet he is longsuffering over them? I say unto you, that he will avenge them speedily. Nevertheless, when the Son of man cometh, shall he find faith on the earth?