The following came from Luther: Letters of Spiritual Counsel. Translated and Edited by Theodore G. Tappert
TO MR. AND MRS. MATTHIAS KNUDSEN.
October 21, 1531
John Knudsen, “of the diocese of Schleswig” near the border of present-day Denmark, was matriculated in the university in Wittenberg on June 7, 1529, and was in all probability the student whose death a little more than two years later led Luther to write the following letter of consolation to the deceased boy’s parents. Nothing is known about the circumstances of his death, but the letter suggests that it followed an illness of some duration. [Text in German; WA, Br, 212, 213.1]
Grace and peace in Christ, our Lord and Saviour.
Honored, dear, good Friends:
The preceptor of your dear son of blessed memory has asked me to write you this letter to console you in the misfortune which, as parents, you have experienced in the death of your son.
It is quite inconceivable that you should not be mourning. In fact, it would not be encouraging to learn that a father and mother are not grieved over the death of their son. The wise man, Jesus Sirach, says this in ch. 22: “Weep for the dead, for light hath failed him; but do not mourn much, for he hath found rest.”
So you too, when you have mourned and wept moderately, should be comforted again. Indeed, you should joyfully thank God that your son had such a good end and that he has gone to sleep in Christ so peacefully that there can be no doubt that he is sleeping sweetly and softly in the eternal rest of Christ. For everyone marveled that he continued steadfast to the end in his prayers and in his confession of Christ. This great blessing should be more agreeable to you than if he had enjoyed all this world’s goods and honors for a thousand years. He has taken with him the greatest treasure he could obtain in this life.
Be of good cheer, therefore. He is well off in comparison with many thousands of others who perish miserably, and sometimes dishonorably, and even die in their sins. Accordingly it is very much to be desired that you and all your loved ones, together with all of us, should by God’s grace have such a death. Your son has cheated the world and the devil while we are still in danger of being overcome by them and are exposed to all the perils against which he is now secure. You sent him to the right school and invested your love and your means very well. God help us to depart in similar fashion. Amen.
The Lord and Supreme Comforter Jesus Christ, who loved your son even more than you did and who, having first called him through his Word, afterward summoned him to himself and took him from you, comfort and strengthen you with his grace until the day when you will see your son again in eternal joy. Amen.
Saturday after Saint Luke, 1531. Martin Luther, Doctor.
 Paul Hockel
 Ecclus. 22:11
 Cf. Matt. 6:20