Here are the three insertions of "Jehovah" in Jude:
Jude 5 NWT: "I desire to remind YOU, despite YOUR knowing all things once for all time, that Jehovah, although he saved a people out of the land of Egypt, afterwards destroyed those not showing faith".
Jude 9 NWT: "But when Mi´cha·el the archangel had a difference with the Devil and was disputing about Moses’ body, he did not dare to bring a judgment against him in abusive terms, but said: “May Jehovah rebuke you."
Jude 14-15 NWT: "Yes, the seventh one [in line] from Adam, E´noch, prophesied also regarding them, when he said: “Look! Jehovah came with his holy myriads, to execute judgment against all, and to convict all the ungodly concerning all their ungodly deeds that they did in an ungodly way, and concerning all the shocking things that ungodly sinners spoke against him."
None of these involve quotations or allusions to the OT. The first is the author's own general comment, reminding his readers of how God destroyed Israelites in the wilderness who disobeyed him; the kurios in this context does not reflect a particular passage. The second is an allusion to the story of Moses' death in the Assumption of Moses, a noncanonical text that was well-known to the early church (cf. Clement of Alexandria, Adumbrationes in Epistulam Judae, 9; Origen, De Principiis 3.2.1, Homilia in Jesu Nave, 2.1; Didymus Caecus, in Epistulam Judae Enarratio, 9; Gelasius Cyzicenus, Historia Ecclesiastica 2.17.17, 2.21.7). It should be obvious to anyone who knows the OT that no such story about Michael the archangel exists in the OT. The NWT instead cites Zechariah 3:2 as the text that supports the insertion of "Jehovah" at Jude 9, but this is a completely different story that concerns Zerubbabel and the high priest Jeshua after the Babylonian exile. What is going on is that the Assumption of Moses reuses material from the OT in composing new narratives; the same thing can be observed in other pseudepigraphal works (see my discussion of OT intertextuality in the first chapter of 1 Enoch). The same sentence ("Let the Lord rebuke you") was utilized in yet another narrative context in the Latin text of the Life of Adam and Eve as what Seth tells a beast that confronts him outside the gates of Eden (39:1). And although the conclusion of the Assumption of Moses is not extant in the sole surviving copy, it is certain that YHWH did not occur in place of "Lord", as the latter is what is used throughout the work — including allusions to passages containing YHWH in the OT (cf. 1:6, 11, 2:2, 7, 9, 3:2, 5, 4:2, 4, 8, 5:4, 9:3, 7, 11:16-17, 12:5-6; compare the formula "thus says the Lord" in 1:11 and the expression kh 'mr yhwh "thus says YHWH" in Jeremiah 26:2 and throughout the Prophets). The third instance of "Jehovah" at Jude 14-15 occurs within a quotation from 1 Enoch 1:9, and the combined witness of the Greek, Latin, and Ethiopic text of this passage shows that neither "Lord" nor YHWH occurred in the original text; kurios is an addition made by the author of Jude in his loose quoting of 1 Enoch. Moreover, the tetragrammaton occurs nowhere else in the extant text of 1 Enoch in the original Aramaic (preserved at Qumran), the Greek, or the Ethiopic. So none of these three insertions of "Jehovah" represent a known quotation or allusion of YHWH in a source used by the author of Jude.
