Oh, taste and see that the LORD is good! Blessed is the man who takes refuge in Him!
Let us consider these matters carefully so that, after we have begun to believe and have hope in the future life that has been granted us through the Word and Baptism, we may learn to endure patiently whatever evils ensue and come to the conclusion that all things take place for our salvation not haphazardly but according to the Father's plan. This is the understanding which we eventually have when the trial is ended. When one is in the very throes of trial, this is not understood, for the feeling of the flesh tears us away from the promise. When a man is involved in tribulation and anxiety, it does not enter his mind to say: "I have been baptized; I have God's promise," but his heart is quite overwhelmed by complaints, grief, and tears according to the flesh. However, the flesh should be crucified and mortified, for it hinders the understanding of the promise and the truth of God's Word, which is perceived in temptation if one clings to it in firm faith. What is stated in the psalm (34:8) follows: "O taste and see that the Lord is good!" God allows us to be tempted that He may have an opportunity for satisfying, comforting, and filling those who have been emptied of all strength and stripped of all help.
From Lectures on Genesis (Luther's Works 6:356-57)