“Whether the original Hebrew text contained the phrase found in the Septuagint cannot be stated with certainty. Whatever the case, God's spirit guided Paul in his quotation, and therefore these words have divine authorization. This does not mean that the entire Septuagint translation is to be viewed as inspired”. (“Insight”, Vol. 1, page 1206)
Another Watchtower absurdity and contradiction. "The entire Septuagint is not inspired, but certain portions do". How convenient !. For instance, if I were Trinitarian I would prefer the Hebrew version of Isaiah 9:6, in which the Messiah is called "Mighty God". On the other hand, if I were Unitarian I would choose the Septuagint which says "the Angel of Great Counsel", instead of "Mighty God". If I were a Jew I would choose the Hebrew version of Isaiah 7:14 which says that Immanuel born from a maiden (almah), but if I were a christian I have to choose the Septuagint, which says "virgin"(greek: parthenos), instead of "maiden". It is a mess.
“That the Christian Greek Scriptures were likewise presented and accepted as inspired is also clear.” (1Co 14:37; Ga 1:8, 1 1, 1 2; 1Th 2:13). (“Insight”, Vol. 1, page 1205)
If I were to accept the letter of Jude as inspired Scripture, I must do the same for the book of 1 Enoch, which is quoted by Jude. Also, in the second century, the Muratorian Canon ignores the letters of Peter and the Apocalypse. Why didn't Paul quote any of the four Gospels? Why does the Gospel of John contradict the synoptics Gospels??