Worthy Is the Lamb and Amen - Handel's "Messiah"

This is what they are singing from:

Rev 5:12  saying with a loud voice, "Worthy is the Lamb who was slain, to receive power and wealth and wisdom and might and honor and glory and blessing!"
Rev 5:13  And I heard every creature in heaven and on earth and under the earth and in the sea, and all that is in them, saying, "To him who sits on the throne and to the Lamb be blessing and honor and glory and might forever and ever!"
Rev 5:14  And the four living creatures said, "Amen!" and the elders fell down and worshiped.