Revelation / Question
The song says the Lamb is worthy to take the scroll and open its seals because he was slain Revelation 5:9. It adds that by his blood he ransomed people for God from every tribe, language, people, and nation Revelation 5:9.
When the Lamb takes the scroll, the inner court of heaven responds with physical and musical worship. The four living creatures and the twenty-four elders fall down before him, holding harps and golden bowls of incense, which the text explains as the prayers of the saints. This scene continues the throne-room vision that began in Revelation 4:1 and moves the focus from the One on the throne to the Lamb who is able to take the sealed scroll. In Revelation 5:1–7 the crisis is that no one is found worthy to open it, until the Lamb appears and receives it.
Revelation 5:8–10 presents the Lamb receiving the scroll and immediately being honored in the same heavenly throne-room setting as God was in chapter 4. The four living creatures and the twenty-four elders fall down before the Lamb, showing that the Lamb is a proper recipient of worship in this vision.
A careful answer keeps the immediate passage, the book's argument, and the whole-Bible storyline together, so the question is answered in context instead of as a detached idea.
Start with Revelation 5:9, then read the surrounding section so the answer stays connected to the passage's flow.
9They sang a new song, saying, "You are worthy to take the book, And to open its seals: For you were killed, And bought us for God with your blood, Out of every tribe, language, people, and nation,