Philippians 4:4 - Albert Barnes' Notes on the Bible

Rejoice in the Lord alway - see the notes at Philippians 3:1. It is the privilege of Christians to do this, not at certain periods and at distant intervals, but at all times they may rejoice that there is a God and Saviour; they may rejoice in the character, law, and government of God - in his promises, and in communion with him. The Christian, therefore, may be, and should be, always a happy man. If everything else changes, yet the Lord does not change; if the sources of all other joy are dried up, yet this is not; and there is not a moment of a Christian’s life in which he may not find joy in the character, law, and promises of God.