The Lord knows those that are his; the world does not. When the mirth of carnal worldlings ceases, the joy of the saints is as lively as ever, because the covenant of grace, the fountain of their comforts, and the foundation of their hopes, never fails. Those who rejoice in the Lord can rejoice in tribulation, and by faith may triumph when all about them are in tears. They encourage their fellow-sufferers to do likewise, even those who are in the furnace of affliction. Or, in the valleys, low, dark, miry places. In every fire, even the hottest, in every place, even the remotest, let us keep up our good thoughts of God. If none of these trials move us, then we glorify the Lord in the fires.It is taken from commentary on Isaiah 24:13-15:
 When thus it shall be in the midst of the land among the people, there shall be as the shaking of an olive tree, and as the gleaning grapes when the vintage is done.  They shall lift up their voice, they shall sing for the majesty of the Lord, they shall cry aloud from the sea.  Wherefore glorify ye the Lord in the fires,  even the name of the Lord God of Israel in the isles of the sea.