And I saw in the right hand of Him who sat on the throne a scroll written inside and on the back, sealed with seven seals. Then I saw a strong angel proclaiming with a loud voice, “Who is worthy to open the scroll and to loose its seals?” And no one in heaven or on the earth or under the earth was able to open the scroll, or to look at it. So I wept much, because no one was found worthy to open and read the scroll, or to look at it. But one of the elders said to me, “Do not weep. Behold, the Lion of the tribe of Judah, the Root of David, has prevailed to open the scroll and to loose its seven seals.” And I looked, and behold, in the midst of the throne and of the four living creatures, and in the midst of the elders, stood a Lamb as though it had been slain, having seven horns and seven eyes, which are the seven Spirits of God sent out into all the earth. Then He came and took the scroll out of the right hand of Him who sat on the throne. Now when He had taken the scroll, the four living creatures and the twenty-four elders fell down before the Lamb, each having a harp, and golden bowls full of incense, which are the prayers of the saints. And they sang a new song, saying: “You are worthy to take the scroll, and to open its seals; for You were slain, and have redeemed us to God by Your blood out of every tribe and tongue and people and nation, and have made us kings and priests to our God; and we shall reign on the earth.” Then I looked, and I heard the voice of many angels around the throne, the living creatures, and the elders; and the number of them was ten thousand times ten thousand, and thousands of thousands, saying with a loud voice: “Worthy is the Lamb who was slain to receive power and riches and wisdom, and strength and honor and glory and blessing!” And every creature which is in heaven and on the earth and under the earth and such as are in the sea, and all that are in them, I heard saying: “Blessing and honor and glory and power be to Him who sits on the throne, and to the Lamb, forever and ever!” Then the four living creatures said, “Amen!” And the twenty-four elders fell down and worshiped Him who lives forever and ever. - Revelation 5
Note here that John cries because no one was found worthy to open and read the scroll. We are not worthy to enter heaven, we in of ourselves are filthy and stained with sin. But, there is one, a perfect Lamb, who is worthy and holy being without blemish or stain and He died for us to be cleansed and washed with His holy blood so we too can enter heaven and live with Him for all eternity. Because of Jesus Christ we are a new creation when we accept Him as Lord and Savior. In all of heaven no person or creature was worthy enough to open and read the scroll, only the Lamb, Jesus Christ the Son of God.
Some people wonder, will there be singing in heaven, verse 9 answers that. "And they sang a new song, saying..." We will all sing and praise God in heaven, but here the four living creatures and the twenty-four elders will be worshiping God with a new song while having harps and golden bowls of incense (the prayers of the saints). Read carefully what their new song is:
“You are worthy to take the scroll, And to open its seals; For You were slain, And have redeemed us to God by Your blood Out of every tribe and tongue and people and nation, And have made us kings and priests to our God; And we shall reign on the earth.”
They are singing how Jesus came to us, died for our sins, redeemed us and reconciled us to God the Father, and adopted us into His family when we accept Him, allowing us to reign with God forever.
Now read carefully what the angels, living creatures, and twenty-four elders proclaim:
“Worthy is the Lamb who was slain To receive power and riches and wisdom, And strength and honor and glory and blessing!”
They are proclaiming the awesomeness and holiness of Jesus Christ and His glory. After telling the story of His abounding love for humans, they then tell of His character and His worthiness to receive all glory and honor.
Next, all creature on heaven, earth, under the earth, and in the seas proclaim:
“Blessing and honor and glory and power Be to Him who sits on the throne, And to the Lamb, forever and ever!”
All creatures will proclaim His royalty and eternal power.
Finally, the four living creatures end with "Amen" and the twenty-four elders fall down and worship Jesus Christ. Amen means "so be it". The living creatures are concluding the worship, praise, and proclamations with "so be it". What a beautiful and power picture of God's holiness, glory, strength, and love.