Answer
In Revelation 10:9, the apostle John asks an angel for the book the angel is holding, and the angel tells John to eat it. What is the little book that John eats (Revelation 10:9), and why is the book significant? The context helps answer those questions.
Revelation 5 presents a scene in heaven of the throne room of God; God has in His right hand a book with seven seals (Revelation 5:1). Jesus is the only one found worthy to open the book and its seals (Revelation 5:6), and when He opens each of the seven seals, there is a corresponding catastrophic judgment event on earth. When the seventh seal is opened, seven trumpets sound, each one beckoning a further judgment. After the sixth trumpet sounds, a strong angel appears, and the angel cried out like a lion’s roar and with thunder (Revelation 10:1–3). As John is about to write down what he heard, he is told not to write the words (Revelation 10:4). The angel then proclaims that there would be no further delay and that “the mystery of God is finished, as He had proclaimed to His servants the prophets” (Revelation 10:7).
Then the voice from heaven prohibiting John from writing what he had heard tells John to “go, take the book which is in the hand of the angel” (Revelation 10:8). John heeds the voice and approaches the angel, requesting to take the book. The angel replies, saying that John should take it and eat it and that it would be sweet in his mouth but would make his stomach bitter (Revelation 10:9). John does eat the book, and it is as the angel said (Revelation 10:10).
This was not the first time a prophet was told to eat a scroll or book. In Ezekiel 2—3 God had a scroll—with words written on front and back just like the book in Revelation—and on this book were written “lamentations, mourning, and woe” (Ezekiel 2:10). God told Ezekiel to eat the scroll, and it was sweet in his mouth like honey (Ezekiel 3:3)—again, just like the book in Revelation. Ezekiel was literally tasting God’s judgment upon Israel and the nations, and John was doing something similar. For centuries up to that point, God had sent His prophets to warn the nations and especially Israel of coming judgments; in Revelation “the mystery of God is finished as He had proclaimed to His servants the prophets” (Revelation 10:7). It appears that the little book that John eats is the book bearing the seals that only the Lamb was worthy to open (as He is the Judge), a book filled with the remaining judgments of God on the nations in fulfillment of the many prophecies He gave during the Old and New Testament eras. Once the final seal had been opened, the judgments in the book were initiated, and the mysteries of God were finished.
In the book of Revelation, God provides a testimony—this one for the churches. The mysteries were now revealed and recorded in the book John wrote. While we aren’t told why the little book that John eats turned his stomach sour, perhaps it was because of what was coming after he ate the book—he had more prophesying to do (Revelation 10:11), and what followed was even worse than what came before. The final judgments in the great tribulation were even more severe. As John recorded the words of the prophecy of the book of Revelation, He records the words of Jesus, who warned that He was the rightful Judge and that He would come suddenly (Revelation 22:12–13). Jesus added that the one who heeds the words of the prophecy of the book of Revelation is blessed.
By reading John’s book we can know how the story will end. How will we prepare? Will we hear and disregard Jesus’ words, or will we heed them and come to Him to take the water of life that costs us nothing (Revelation 22:17)?