“Rejoice in the Lord alway: and again I say, Rejoice.” Philippians 4:4

The apostle Paul “rejoiced always in the Lord; in Him is that which nothing can alter.
This is not an indifference to sorrow which hinders weeping, but it is a spring of joy
which enlarges when there is distress, because of its [unchanging] and which
becomes even more pure in the heart the more it becomes the only one; and it
is in itself the only spring that is infinitely pure. When it is our only spring, we
thereby love others. If we love them besides Him, we lose something of Him.
When through exercise of heart we are weaned from all other springs, His joy
remains in all its purity, and our concern for others partakes of this same
purity. Nothing troubles this joy, because Christ never changes. The better we
know Him, the better are we able to enjoy that which is ever enlarging through
knowing Him. But he exhorts Christians to rejoice: it is a testimony to the worth
of Christ, it is their true portion. Four years in prison chained to a soldier had
not hindered his doing it, nor being able to exhort others more at ease than he.”
(Philippians, J.N. Darby)