The Lord said, through Joseph Smith:

"For my soul delighteth in the song of the heart; yea, the song of the righteous is a prayer unto me, and it shall be answered with a blessing upon their heads."
Doctrine and Covenants 25:12

"And it shall come to pass that the righteous shall be gathered out from among all nations, and shall come to Zion, singing with songs of everlasting joy."
Doctrine and Covenants 45:71

"And the graves of the saints shall be opened; and they shall come forth and stand on the right hand of the Lamb, when he shall stand upon Mount Zion, and upon the holy city, the New Jerusalem; and they shall sing the song of the Lamb, day and night forever and ever."
Doctrine and Covenants 133:56