Isaiah 59:17 (Old Testament)
Ephesians 6:11 (New Testament)
Wisdom of Solomon 5:17-20 (Apocrypha)
Paul's description of the armor of God in Ephesians 6 is likely influenced by Isaiah 59:17 which is very similar. Additionally, Paul may have been including content from the apocryphal book, Wisdom of Solomon: "The Lord will take his zeal as his WHOLE ARMOR, and will arm all creation to repel his enemies; he will put on righteousness as a breastplate, and wear a helmet of righteous justice; he will take holiness as an invincible shield, and sharpen stern wrath for a sword" (Wisdom of Solomon 5.17-20)
Bobby Valentine notes: "One of the most interesting parallels between Paul and Wisdom is with the word "panoplia" (whole armor). This word ONLY occurs twice in all biblical Greek. Guess where? You got it: in Ephesians 6 and Wisdom 5.17. (I say biblical Greek because Wisdom is part of the LXX which is in fact "biblical" Greek). ... Both Wisdom and Ephesians are clearly reflecting back Isaiah 59. But interestingly Paul includes two things that Isaiah 59 did not: 1) the shield and 2) the sword. Significantly enough Wisdom includes both of these."