Now, what He intends to say is this: “I have given you instructions about how you ought to live and what you ought to watch out for. In addition, it is necessary that you ask and that you have the confidence to go right on seeking and knocking without becoming lazy or lax in it. You will have need of asking, seeking, and knocking. Though doctrine and life may both have begun all right, we shall have to suffer from all sorts of transgressions and offenses that hinder us daily and keep us from progressing. We battle against these continually with all our might, but the strongest shield we have is prayer. If we do not use that, it is impossible for us to hold our own and to go on being Christians. We can plainly see now not only the sort of obstacles that oppose the Gospel every day, but also our own neglect of prayer and our attitude, as though this warning and admonition did not refer to us and we did not need prayer any more, now that the useless chattering and muttering of the rosaries and the other idolatrous prayers have stopped. All this is not a good sign, and it makes me afraid that some great misfortune which we could have prevented will overtake us. (Luther’s Works, v. 21, pages 229).

Matthew 7:7. Ask, and it will be given you; seek, and you will find; knock, and it will be opened to you.  8. For every one who asks, receives, and he who seeks, finds, and to him who knocks it will be opened.  9. Or what man of you, if his son asks him for a loaf, will give him a stone? 10. Or if he asks for a fish, will give him a serpent? 11. If you, then, who are evil, know how to give good gifts to your children, how much more will your Father who is in heaven give good things to those who ask Him?

After teaching His disciples and instituting the office of the ministry, telling them what they are expected to preach and how they are to live, Christ, the Lord, now adds an admonition to prayer. By this He intends to teach them that, second only to the office of preaching, prayer is the chief work of a Christian and an inseparable part of the sermon. He also wants to indicate that because of all the temptations and hindrances we face, nothing is more necessary in Christendom than continual and unceasing prayer that God would give His grace and His Spirit to make the doctrine powerful and efficacious among us and among others. That is why, in the words we quoted from the prophet Zechariah (Zech. 12:10), God promised that He would pour out upon the Christians a Spirit of grace and of supplication. In these two items He summarizes all Christian existence. (Luther’s Works, v. 21, pages 228-229).