2 Chronicles 30:27 - Joseph Benson’s Commentary on the Old and New Testaments

Then the priests the Levites arose, and blessed the people That is, those of the Levites who were priests also, for to them only this work belonged, 1 Chronicles 23:13. In performing this office, they were both the people's mouth to God, by way of prayer, and God's mouth to the people, by way of promise; for the blessing included both. And in it they testified both their desire of the people's welfare, and their dependance upon God and the word of his grace, to which they commended them. And their prayer came up to his holy dwelling-place The voice of the priests, when they thus blessed the people, as God had commanded, was heard in heaven. God said amen to their prayer, and perhaps gave some sensible token of the ratification of the blessing which they had pronounced. The prayer that comes up to heaven in a cloud of incense, will come down again to this earth in showers of blessings.