Jesus told his disciples a parable to show that they should always keep on praying and never be discouraged. This parable is named "The Parable of the Unjust Judge."
"In a certain city," he said, "there was a judge who in his rule did not try to do right, but was often unjust and wicked; for he had no fear of God and no care for what men said about him. And in that city there was a widow who came many times to this judge, crying over and over again, 'Do for me what is right against the man who has done me wrong!'
"For some time the judge paid no attention to her, for right and wrong were both the same to him. But after a while the judge said to himself:
"'Although I have no fear of God and no care for man, yet as this widow is so troublesome to me, and gives me no rest, I will do what she asks, for I am tired of her coming and of her calling out for her right every day.'
"Listen," said the Lord Jesus, "to what this unjust judge says. And if a man who does not care for right or wrong will at last answer a prayer, how much more will your heavenly Father listen to his own children when they call upon him day and night, even though he seems to make them wait long for the answer to their prayers?
I tell you that God will do right by them and answer their prayers, and that very soon! Yet when the Son of Man comes, will he find on earth those who are looking for him and who believe in him?"