Revelation 14:5

in their mouth
Scripture implicates the mouth as the organ which speaks forth the heart: “Brood of vipers! How can you, being evil, speak good things? For out of the abundance of the heart the mouth speaks” (Mtt. Mat. 12:34); “These people draw near to Me with their mouth, and honor Me with their lips, but their heart is far from Me” (Mtt. Mat. 15:8); “But those things which proceed out of the mouth come from the heart, and they defile a man” (Mtt. Mat. 15:18); “For with the heart one believes unto righteousness, and with the mouth confession is made unto salvation” (Rom. Rom. 10:10). The tendency of the tongue toward evil, and the immense difficulty with which it is harnessed is a frequent theme of Scripture.¹ These are standing upon Mount Zion, God’s holy hill:

LORD, who may abide in Your tabernacle? Who may dwell in Your holy hill? He who walks uprightly, and works righteousness, and speaks the truth in his heart; He who does not backbite with his tongue, nor does evil to his neighbor, nor does he take up a reproach against his friend. (Ps. Ps. 15:1-3) [emphasis added]

May their obedient and dedicated state before the Lamb be ever before us as motivation in our walk during the present age! was found no deceit
Their mouths are to be contrasted with the blasphemous mouth of the Beast. See commentary on Revelation 13:5. Unlike the masses upon the earth at the time of their ministry, they do not mouth the lie (2Th. 2Th. 2:11). Their mouths are like that of wisdom and of the Lamb:

Listen, for I will speak of excellent things, and from the opening of my lips will come right things; for my mouth will speak truth; wickedness is an abomination to my lips. All the words of my mouth are with righteousness; nothing crooked or perverse is in them. (Pr. Pr. 8:6-8)

And they made His grave with the wicked-But with the rich at His death, because He had done no violence, nor was any deceit in His mouth. (Isa. Isa. 53:9)

They are firstfruits in at least two ways: they are the first among many redeemed Jews during the Tribulation and they are the first among a purified Israel which will result from the time of Jacob’s Trouble:

I will leave in your midst a meek and humble people, and they shall trust in the name of the LORD. The remnant of Israel shall do no unrighteousness and speak no lies, nor shall a deceitful tongue be found in their mouth; for they shall feed their flocks and lie down, and no one shall make them afraid. (Zep. Zep. 3:12-13)

They represent the early stages of the glorious promise made to Israel as part of her New Covenant:

But this is the covenant that I will make with the house of Israel after those days, says the LORD: I will put My law in their minds, and write it on their hearts; and I will be their God, and they shall be My people. No more shall every man teach his neighbor, and every man his brother, saying, ‘Know the LORD,’ for they all shall know Me, from the least of them to the greatest of them, says the LORD. For I will forgive their iniquity, and their sin I will remember no more. (Jer. Jer. 31:33-34)

without fault
Ἄμωμοι [Amōmoi] , used “of the absence of defects in sacrificial animals,”² spotless. Applied to these, it denotes being blameless.³ “In the Septuagint, amōmos is used as an ethical term and consistently refers to the holy behavior of the faithful (Ps. Ps. 119:1; Pr. Pr. 11:5) and, on occasion, is even applied as a title of honor to God himself (Ps. Ps. 18:30). . . . Christ was amōmos because there was no spot or blemish in him. Thus he could ask: ‘Which of you convicts Me of sin?’ (John John 8:46).”⁴ As exemplary as their conduct has been during their ministry, this speaks of something far beyond what they themselves were able to exhibit. before the throne of God
This phrase does not appear in the NU or MT texts, but only in the TR text. It may have been added in an attempt to equate the 144,000 with those who sing before the throne, the living creatures, and the elders (Rev. Rev. 14:3+). However, the singers may be the harpists. See commentary on Revelation 14:1. The phrase “without fault before the throne of God” can be seen in terms of a heavenly scale of perfection. On one end is fault. On the other end is God. How can these two be found together? Only because the central mechanism of the scale is the cross of Christ, the “tree of life!” Having been redeemed and washed by His blood (Rev. Rev. 1:5+), they stand clothed in the perfection of the Son before the Father. All their sins are cast behind them (Isa. Isa. 38:17) and they are without spot or wrinkle (Eph. Eph. 5:27). They are holy and blameless in His sight (Col. Col. 1:22). They are “faultless before the presence of God” (Jude Jude 1:24).

---

Notes

¹ Concerning the need to tame the tongue: Ps. Ps. 5:9; Ps. 17:3; Ps. 19:14; Ps. 39:1; Ps. 120:1-7; Ps. 141:3; Pr. Pr. 10:19, Pr. 10:31-32; Pr. 15:2, Pr. 15:4; Pr. 15:28; Pr. 18:21; Pr. 21:23; Isa. Isa. 6:5, Isa. 6:7; Isa. 59:3; Mtt. Mat. 12:34-35; Mat. 15:18; Jas. Jas. 1:26; Jas. 3:6-Jas. 3:8.

² Frederick William Danker and Walter Bauer, A Greek-English Lexicon of the New Testament and Other Early Christian Literature (Chicago, IL: University of Chicago Press, 2000), 47.

³ Ibid.

⁴ Richard Chenevix Trench, Commentary on the Epistles to the Seven Churches in Asia (Eugene, OR: Wipf and Stock Publishers, 1861), 402.