Charles H. Spurgeon on Psalms 33:1

Rejoice in the Lord. Joy is the soul of praise. To delight ourselves in God is most truly to extol him, even if we let no notes of song proceed from our lips. That God is, and that he is such a God, and our God, ours for ever and ever, should wake within us an unceasing and overflowing joy. To rejoice in temporal comforts is dangerous, to rejoice in self is foolish, to rejoice in sin is fatal, but to rejoice in God is heavenly. He who would have a double heaven must begin below to rejoice like those above. O ye righteous. This is peculiarly your duty, your obligations are greater, and your spiritual nature more adapted to the work, be ye then first in the glad service. Even the righteous are not always glad, and have need to be stirred up to enjoy their privileges. For praise is comely for the upright. God has an eye to things which are becoming. When saints wear their choral robes, they look fair in the Lord's sight. A harp suits a blood washed hand. No jewel more ornamental to a holy face than sacred praise. Praise is not comely from unpardoned professional singers; it is like a jewel of gold in a swine's snout. Crooked hearts make crooked music, but the upright are the Lord's delight. Praise is the dress of saints in heaven, it is meet that they should fit it on below.