Some movies end with a door left open to a sequel. The writers wrap up most of the plotlines but leave one conspicuously open. This will become the launch point for the follow-up. In a way, the book of Psalms ends in this manner. The final psalm comes to a close, but it leaves a loose end dangling.
Psalm 150 is a psalm of closure. It is the last in a group of five songs (Psalm 146–150) that begin and end with the Hebrew phrase Hallelu Yah (Hallelujah!), which means “Praise the Lord.” It completes the book of Psalms, a fitting doxology with an extended call to praise. But it also concludes the fifth book in Psalms, stretching from Psalm 107–150. This book does not close in quite the same way as the other four books in Psalms.
The first four books of the Psalms end with “Amen,” a word of tight closure that means “so be it.” (See Psalms 41; 72; 89; 106.) It is a fitting capstone to what has gone before, a latch to close the door tightly on all that has been expressed in the preceding collection of psalms. There is agreement to what has been expressed. But Psalm 150 has no “Amen.” Instead it ends with Hallelu Yah, an invitation to praise the Lord.
This leaves the psalm surprisingly open-ended. The psalmist issues a summons to praise with no response given. God awaits our RSVP. This catalog of 150 songs has not exhausted our praise. Everything that has breath receives an invitation to join in the chorus of praise and add its voice. The praise that unfolds throughout the Psalms will continue beyond the confines of the book. Our own praise becomes the sequel, an opportunity to add our own psalm to the collection. This ongoing worship expressed by those who accept the invitation will be the “Amen” that has been left unsaid.