Psalms 46:

"GOD is our refuge and strength, a very present help in trouble." (This psalm is a song for Israel, for all who are truly the chosen of God, called to be his own people. The peace of God that passes all understanding should keep the hearts and minds of all who rest in God (Php 4:7). If, indeed, the Lord is our refuge and strength, we are entitled to seek after a spirit that will bear us above the dreads of common men. Not everyone can sing this psalm of peace amid commotion and calamity. We must belong to the believing company; we must have the Lord as our God; and we must have learned the art of prevailing prayer. No man can truly sing this psalm but those who are redeemed from the earth. Martin Luther delighted to sing this psalm. In the days of the most furious opposition, he was known to say to Melancthon, "Come, let us sing the forty-sixth psalm, and let the devil do his worst." So, too, when Luther was dead, Melancthon heard a girl singing this psalm, and he said to her, "Sing on, dear daughter of mine, you know not what comfort you bring to my heart." So the young, the simple, and the guileless may sing what strengthens the nerves of warriors for battle).

Charles H. Spurgeon