Psalms 149:5

Let the saints be joyful in glory: let them sing aloud upon their beds.

The saints are summoned to be joyful in glory, expressing that joy openly and audibly. That rejoicing is to continue even in the quiet and privacy of rest, with singing aloud upon their beds. Such joyful singing belongs to the praise rendered to God as an act of worship. It is offered to a God who takes pleasure in His people and who beautifies the meek with salvation.