Revelation 10

Rev. 10:1 another mighty angel... clothed with a cloud: and a rainbow was upon his head

Joseph Smith taught, "There are two kinds of beings in heaven, namely: Angels, who are resurrected personages... Secondly: the spirits of just men made perfect." (D&C 129:1) When we read of this angel with a face as the sun and feet as pillars of fire, we should immediately recognize that this angel is a glorified and resurrected being. "These are they whose bodies are celestial, whose glory is that of the sun, even the glory of God." (D&C 76:70).
How are we to understand the significance of the cloud and the rainbow? The rainbow is reminiscent of the writings of Ezekiel who described the throne of God, "As the appearance of the bow that is in the cloud in the day of rain, so was the appearance of the brightness round about." (Ezek. 1:28) Similarly, John described God's throne with "a rainbow round about... in sight like unto an emerald." (Rev. 4:3) From these passages we conclude that the angel is not only resurrected but exalted. The rainbow represents his exalted status as a god with a throne of his own. The identity of this angel is Michael, the archangel (compare Rev. 10 with D&C 88:110-112). We should not be surprised to find out John saw him as an exalted being. The Lord declared that Abraham had "entered into his exaltation and sitteth upon his throne;" that he with Isaac and Jacob "have entered into their exaltation, according to the promises, and sit upon thrones, and are not angels but gods." (D&C 132:29, 37) If Abraham had been resurrected at the time of Christ to inherit his exaltation, then wouldn't Adam have received the same glory?

Rev. 10:2 he set his right foot upon the sea, and his left foot on the earth

The imagery of having one foot on land and one on the sea is symbolic of this Michael's priesthood power. He has power over land and sea. The exercise of his priesthood keys will require dominion over both. He helped to create land and sea; now he will exercise authority over both.

Rev. 10:4 seal up those things which the seven thunders uttered, and write them not

Since Nephi was told not to write the things of John's revelation (1 Ne. 14:25), we might have assumed that John would reveal it all. He does not. We, or the world, must not be ready to hear "those things which the seven thunders uttered." Just as well. They are probably seven more destructions pronounced as "the testimony of the voice of thunderings." (D&C 88:89)

Rev. 10:5-6 the angel... sware by him that liveth for ever and ever... that there should be time no longer

Michael is not declaring the end of time. The language may imply this, but it just can't be. In the very next chapter, there are six separate references to time. How could there be "time no longer" right before John describe the Gentiles treading the holy city under foot for forty and two months (Rev. 11:2)? That doesn't make sense. Secondly, we know that Christ came in "the meridian of time" (D&C 20:26; 39:3). If time on earth ends at the beginning of the seventh seal, then Christ should have been born 1000 BC in order for his first advent to occur in the meridian of time. So how are we to understand this term?
As usual, we must turn to modern revelation and exercise a portion of the spirit of prophecy. Consider similar references in the Doctrine and Covenants:
...the seventh angel shall sound his trump; and he shall stand forth upon the land and upon the sea, and swear in the name of him who sitteth upon the throne, that there shall be time no longer; and Satan shall be bound, that old serpent, who is called the devil, and shall not be loosed for the space of a thousand years. (D&C 88:110)
And Satan is bound and time is no longer... (D&C 84:100)
Note that the D&C references associate this declaration with Satan being bound for 1000 years. When Satan was sent to the earth in the first place, his fury was fanned by the realization that he had little time, "for the devil is come down unto you, having great wrath, because he knoweth that he hath but a short time." (Rev. 12:12) Michael's declaration that "there should be time no longer" is not directed to the world but to Satan himself. The devil's time is up. He has no more opportunity to afflict and torment man; there is "time no longer" to lull mankind into a false sense of security; there is "time no longer" to bind the children of men with his strong cords and chains of darkness; there is "time no longer" to expand the number of his miserable minions. In effect, Michael is declaring war on Satan and his forces-yet again (see Rev. 12:7). Hereby we assume it is Michael who is the angel who holds the keys to lay "hold on the dragon, that old serpent, which is the Devil, and Satan, and [bind] him a thousand years." (Rev. 20:2)

Rev. 10:7 in the days of the... seventh angel... the mystery of God should be finished

What is the mystery of God? What work is it that He must accomplish? First of all, the 144,000 must be sealed (Rev. 7), but secondly John's mission must be accomplished-to gather Israel and restore all things (D&C 77:14). The latter two have been a particular focus of all the prophets. Christ can't come "until the times of restitution of all things, which God hath spoken by the mouth of all his holy prophets since the world began." (Acts 3:21)

Rev. 10:8-9 Go and take the little book... and eat it up; and it shall make thy belly bitter, but it shall be in thy mouth sweet as honey

Q. What are we to understand by the little book which was eaten by John, as mentioned in the 10th chapter of Revelation?
A. We are to understand that it was a mission, and an ordinance, for him to gather the tribes of Israel; behold, this is Elias, who, as it is written, must come and restore all things.
(D&C 77:14)
Perhaps it seems strange to eat a book. The imagery is symbolic of accepting an assignment from the Lord. Ezekiel was also asked to eat a book. His mission was the same as John's, "when I looked, behold... and, lo, a roll of a book was therein; And he spread it before me; and... said... eat this roll, and go speak unto the house of Israel. So I opened my mouth, and he caused me to eat that roll." (Ezek. 2:3-3:2) The roll is both bitter and sweet-sweet because so many souls will be saved by his ministry among the house of Israel-and bitter because many others would reject the gospel of Christ and suffer the judgments of God.
What was John's mission? It was to gather the twelve tribes of Israel. This began with his mortal ministry and continued with his appearance to Joseph Smith and Oliver Cowdery to restore the Melchizedek Priesthood. Furthermore, he has worked as a translated being among the lost ten tribes-preparing them for the Second Coming of Christ. His mission has been to restore the priesthood to the earth and to restore the House of Israel according to the great promises made to their fathers.
John Whitmer
The spirit of the Lord fell upon Joseph in an unusual manner. And prophesied that John the Revelator was then (June 1831) among the ten tribes of Israel who had been led away by Salmanasar King of [Assyria], to prepare them for their return, from their long dispersion, to again possess the land of their fathers. (The Book of John Whitmer, typescript, [Provo: BYU Archives and Manuscripts], chap. 7)

Rev. 10:11 thou must prophesy again before many peoples and nations

Gerald N. Lund
The "little book" chapter at first seems totally out of place and not part of the chronological flow. A mighty angel appears, gives John a small book, and requests that he eat it. When John does so, he finds it as "sweet as honey" in his mouth, but it makes his "belly bitter" (Rev. 10:1-11).
...He was told that "it was a mission, and an ordinance, for him [John] to gather the tribes of Israel" (D&C 77:14; 7:3). In other words, in the midst of the vision of the last days, it is as if the Lord pauses and says to John, "Since you will live during these times, you may wish to know what you'll be doing. Here is your mission and calling." (Selected Writings of Gerald N. Lund: Gospel Scholars Series [Salt Lake City: Deseret Book Co., 1999], 77.)