Luke 11:1-10

And it came to pass, that as he was in a certain place praying, when he ceased, one of his disciples said to him: Lord, teach us to pray, as John also taught his disciples. And he said to them: When you pray, say: Father, hallowed be thy name. Thy kingdom come. Give us this day our daily bread. And forgive us our sins, for we also forgive every one that is indebted to us. And lead us not into temptation.

And he said to them: Which of you shall have a friend, and shall go to him at midnight, and shall say to him: Friend, lend me three loaves, Because a friend of mine is come off his journey to me, and I have not what to set before him. And he from within should answer, and say: Trouble me not, the door is now shut, and my children are with me in bed; I cannot rise and give thee. Yet if he shall continue knocking, I say to you, although he will not rise and give him, because he is his friend; yet, because of his importunity, he will rise, and give him as many as he needeth. And I say to you, Ask, and it shall be given you: seek, and you shall find: knock, and it shall be opened to you. For every one that asketh, receiveth; and he that seeketh, findeth; and to him that knocketh, it shall be opened.

Commentary
from the Catholic Encyclopedia

The friend at midnight and the unjust judge need no explanation. With a certain strength of language both dwell on the power of continued prayer. Importunity wins, "the kingdom of heaven suffereth violence, and the violent bear it away" (Matthew 11:12). Dante has beautifully expressed the Divine law which these parables teach (Paradiso, xx, 94-100).