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).

Similarly, true and pious preachers will faithfully seek only the welfare and the salvation of all people. They will not impose any burden on them, either in their consciences or even outwardly in their temporal possessions and physical existence. Whoever despises them should know that he is not a Christian and that he has lost the treasure once more. Our preaching and admonition is for everyone who will accept it and agree with us. Whoever refuses to do so and yet uses the name of the Gospel or the pretense of Christian brotherhood to despise us and to trample us underfoot, against him we use the art of letting him keep the pretense but actually taking everything back, so that he has nothing left at all. We have the command to separate ourselves from such people. We do not enjoy doing it, and we would have preferred to have them stay with us. But since they refuse, we must let them go and not let them ruin our treasure or trample it underfoot.  (Luther’s Works, v. 21, pages 228).