The clearest references to the two witnesses are located in lds.org. Quotation contain a reference from the link https://www.lds.org/manual/old-testament-student-manual-kings-malachi/enrichment-i?lang=eng
"(I-4) Armageddon: The Participants
Ezekiel and Jeremiah indicated areas that will be involved and named Israel as the target of the war:
Ezekiel named Gog of the land of Magog, the prince of Meshech and Tubal, as the leader of the forces that would come against Israel (see Ezekiel 38:1–3). Magog, Meshech, and Tubal were ancient peoples in the northern part of Asia Minor (see Notes and Commentary on Ezekiel 38:2–6). Gog is a symbolic name for the leader or leaders of this great evil power that will arise in the last days.
Ezekiel named Persia, Ethiopia, Libya, Gomer, and Togarmah as being in alliance with Gog (see Ezekiel 38:2–6; see also Notes and Commentary on Ezekiel 38:2–6 and the Bible Dictionary).
These designations refer to general areas of the ancient world, so a list of modern nations fighting in Armageddon cannot be compiled from these sources. Elder Bruce R. McConkie said: “The prophecies do not name the modern nations which will be fighting for and against Israel, but the designation Gog and Magog is given to the combination of nations which are seeking to overthrow and destroy the remnant of the Lord’s chosen seed.” (Mormon Doctrine, p. 298.)
The prophets agreed that all nations should be joined in this alliance in one way or another (see Jeremiah 25:26; Joel 3:1; Zechariah 14:2; Revelation 16:14).
The strategic objective of this great and evil alliance is clearly the nation of Israel (see Ezekiel 38:8, 15–16; Joel 2:1; 3:1–2; Zechariah 14:2).
(I-5) Armageddon: The Army of Gog
Several of the prophets vividly described in figurative language the power and massiveness of this army.
Ezekiel described it as “clothed with all sorts of armour, even a great company with bucklers and shields, all of them handling swords” (Ezekiel 38:4) and as coming like “a storm” and “a cloud to cover the land” (v. 9), having “many people” with him, “all of them riding upon horses [a symbol of power in war], a great company, and a mighty army” (v. 15).
Daniel described the “king of the north” as coming with a “great army” which others have no “strength to withstand” (Daniel 11:13, 15) and as coming “like a whirlwind, with chariots, and with horsemen, and with many ships; and he shall enter into the countries, and shall overflow and pass over” (v. 40). Elder Joseph Fielding Smith specifically identified Daniel 11–12as referring to the last days (see Signs of the Times, p. 156).
Joel stated that the army would be the greatest army in the history of the world up to that point (Joel 2:2). He described it as being like a “fire” that devours the land, leaving what had looked like the “garden of Eden” before their coming as “a desolate wilderness” (Joel 2:3; see also Joel 2:2, 4–5). Joel also said that the army would be highly disciplined in warfare and virtually invincible: “When they fall upon the sword, they shall not be wounded” (Joel 2:8; see also Joel 2:7, 9).
John the Revelator used the imagery of a cloud of locusts (vast numbers that bring great devastation) and described the army as having the “teeth of lions,” “breastplates of iron,” and “wings” that sounded like the “sound of chariots of many horses running to battle” (Revelation 9:8–9). The army was numbered “two hundred thousand thousand” (Revelation 9:16), having “breastplates of fire, and of jacinth, and brimstone” and with “fire and smoke and brimstone” issuing “out of their mouths” (Revelation 9:17). Elder Bruce R. McConkie, referring to the imagery of John and Joel, suggested that “it is not improbable that these ancient prophets were seeing such things as men wearing or protected by strong armor; as troops of cavalry and companies of tanks and flame throwers; as airplanes and airborne missiles which explode, fire shells and drop bombs; and even other weapons yet to be devised in an age when warfare is the desire and love of wicked men” (Doctrinal New Testament Commentary, 3:503).
It will be partly through the aid of false religionists working miracles that so many people join in this unholy alliance (see Revelation 13:11–15; 19:20). Elder Orson Pratt taught that “so great will be the darkness resting upon Christendom, and so great the bonds of priestcraft with which they will be bound, that they will not understand, and they will be given up to the hardness of their hearts. Then will be fulfilled that saying, That the day shall come when the Lord shall have power over his Saints, and the Devil shall have power over his own dominion. He will give them up to the power of the Devil, and he will have power over them, and he will carry them about as chaff before a whirlwind. He will gather up millions upon millions of people into the valleys around about Jerusalem in order to destroy the Jews after they have gathered. How will the Devil do this? He will perform miracles to do it. The Bible says the kings of the earth and the great ones will be deceived by these false miracles. It says there shall be three unclean spirits that shall go forth working miracles, and they are spirits of devils. Where do they go? To the kings of the earth; and what will they do? Gather them up to battle unto the great day of God Almighty. Where? Into the valley of Armageddon.” (In Journal of Discourses, 7:189.)
(I-6) Gog Will Be Thwarted by the Power of Two Witnesses
One question that arises as one studies the prophetic picture is, How could a nation as tiny as modern Israel stand against the combined armies of the world? The answer lies in an understanding of the role of two important participants in these great events.
John the Revelator gave the most detailed picture of these two participants. They are called the “two witnesses,” the “two olive trees” and the “two candlesticks” (Revelation 11:3–4). Latter-day revelation teaches that they are “two prophets … raised up to the Jewish nation” who will “prophesy to [them] after they are gathered and have built … Jerusalem” (D&C 77:15).
Elder Bruce R. McConkie wrote:
“These two shall be followers of that humble man, Joseph Smith, through whom the Lord of Heaven restored the fulness of his everlasting gospel in this final dispensation of grace. No doubt they will be members of the Council of the Twelve or of the First Presidency of the Church. Their prophetic ministry to rebellious Jewry shall be the same in length as was our Lord’s personal ministry among their rebellious forebears.
“The two olive trees, and the two candlesticks [are] symbols of the two witnesses; meaning, perhaps, that as olive trees, they shall provide oil for the lamps of those who go forth to meet the Bridegroom; … and that as lamp stands they shall reflect to men that light which comes from Him who is the Light of the World.” (Doctrinal New Testament Commentary, 3:509–10.)
These prophets will have power to pronounce great judgments upon the earth (see Revelation 11:5–6).
“They shall have power like Elijah who called down fire from heaven to consume his enemies, and who sealed the heavens that it rained not in all Israel for the space of three and a half years (1 Kings 17and 18; 2 Kings 1), and like Moses by whose word blood and plagues lay heavily upon the Egyptians. (Ex. 7, 8, 9, and 10.)” (McConkie, Doctrinal New Testament Commentary, 3:510.)
Their miraculous power seems to be the force preventing Gog and his army from succeeding in annihilating Israel. Elder Parley P. Pratt wrote: “John, in the eleventh chapter of Revelation, gives us many more particulars concerning this same event. He informs us that after the city and temple are rebuilt by the Jews, the Gentiles will tread it under foot forty and two months, during which time there will be two prophets continually prophesying and working mighty miracles. And it seems that the Gentile army shall be hindered from utterly destroying and overthrowing the city, while these two prophets continue.” (A Voice of Warning,p. 33.)
Isaiah called these prophets “two sons” and said they were the only hope of deliverance for Israel because they would be “full of the fury of the Lord” (JST, Isaiah 51:19–20; see also JST, Isaiah 51:17–18).
(I-7) Armageddon: The Final Extremity
John showed that eventually the two prophets will be captured and killed by the opposing army, and their bodies will be left in the streets of Jerusalem for “three days and an half” as the forces of evil engage in a great celebration over their death (Revelation 11:9; see also Revelation 11:7–8, 10).
“That level of spiritual debauchery is shown forth by the fact that the wicked not only slay the prophets of God, but boast of their deeds and glory in them. Such people, as the Jaredites and Nephites before them, are ripened in iniquity and are ready for that destruction and burning which shall cleanse the vineyard of corruption when Jesus descends with his chariots of fire.” (McConkie, Doctrinal New Testament Commentary,3:510.)
During the “three days and an half” that the prophets lie dead in the streets, the army will ravage the city of Jerusalem and the remaining population of Israel (Revelation 11:9). Elder Pratt explained: “After a struggle of three years and a half, they [Gog’s army] will at length succeed in destroying these two prophets and then overrunning much of the city; they will send gifts to each other because of the death of the two prophets, and in the meantime will not allow their dead bodies to be put in graves, but will suffer them to lie in the streets of Jerusalem three days and a half, during which time the armies of the Gentiles, consisting of many kindreds, tongues, and nations, passing through the city, plundering the Jews, will see their dead bodies lying in the street.” (Voice of Warning, p. 33.)
Zechariah says that only one-third of the nation of Israel will survive this final extremity when the “city [Jerusalem] shall be taken, and the houses rifled [looted], and the women ravished; and half of the city shall go forth into captivity” (Zechariah 14:2; see also Zechariah 13:8–9; 14:1).
(I-8) Armageddon: The Deliverance
In what will be one of the blackest moments of Israel’s history, just as it appears that they are about to be annihilated, the Lord’s fury will be unleashed upon the kingdoms of the world (see Ezekiel 38:18), and the Lord will “go forth, and fight against those nations” (Zechariah 14:3).
The two prophets, lying dead in the streets of Jerusalem, will be resurrected in the sight of the people (see Revelation 11:11–12): “After three days and a half, on a sudden, the spirit of life from God will enter them; they will arise and stand upon their feet, and great fear will fall upon them that see them. And then they shall hear a voice from heaven saying, ‘Come up hither,’ and they will ascend up to heaven in a cloud, with their enemies beholding them.” (Pratt, Voice of Warning,p. 33.)"