1 Chronicles 16:36

Blessed be the LORD God of Israel for ever and ever. And all the people said, Amen, and praised the LORD.

The blessing of the Lord God of Israel forever and ever was spoken when the ark of the covenant was brought into the City of David. On that occasion a psalm of joy and triumph was chanted, closing with the call for blessing and the people's answer.

That setting establishes the pattern that praise to the Lord belongs in the congregation of His people. It commands God's people to praise the Lord together, with all the people joining by saying Amen. The fervent response of Amen and praise was evidence that they understood the word spoken. By that answer they joined in the worship of God.