Therefore every Christian should pay attention to this admonition. It is, in the first place, a commandment, as much as the previous statement, “Judge not” is a commandment. He should know that he is obliged to practice this Christian work. He should not be like that peasant who said: “I give grain to my minister, and he prays for me”; or like the people who think: “What is the use of my praying? If I do not pray, others do.” We must not suppose that it is no concern of ours or that it is left up to our free choice; but I have given more detailed admonition on this elsewhere.15 In the second place, you have here the comforting promise and rich assurance that He attaches to prayer, to make it evident that He cares about it and to teach us to think about prayer as something dear and precious before God, because His admonition is so serious and His invitation so friendly, and He promises that we shall not ask in vain. Even if we had no other reason or attraction than this rich and friendly word, it should be enough to prompt us to pray. I shall not even talk about how dear His exhortation is or how sublime His command or how desperate our need. (Luther’s Works, v. 21, pages 229-230).