There are several scripture quotes in the New Testament that are found only in the LXX:
1) Let all God’s angels worship him. Hebrews 1:6, Deuteronomy 32:43 LXX
2) According to Luke, Jesus read from the scroll in the synagogue in Nazareth and quotes from the LXX:
He has sent Me to heal the brokenhearted,
To proclaim liberty to the captives
And recovery of sight to the blind . . . Luke 4:18, Isaiah 61:1 LXX
3) The apostle met in Jerusalem to discuss gentile converts and quoted this passage from LXX Amos:
So that the rest of mankind may seek the Lord,
Even all the Gentiles who are called by My name . . . Acts 15:17, Amos 9:12 LXX
The modern Hebrew text says nothing about gentiles seeking the Lord:
That they may possess the remnant of Edom,
And all the Gentiles who are called by My name . . . Amos 9:12 NKJV
Greek-speaking Jews, such as the Bereans and the Timothy's family, used the LXX as their scriptures and it had a larger canon than that used by the Pharisees in Jerusalem. These scriptures were the original Christian bible and became the basis for the Christian Old Testament. They are the scriptures that Paul specifically praises in this passage:
. . . from childhood you have known the Holy Scriptures, which are able to make you wise for salvation through faith which is in Christ Jesus. All Scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness . . . 2 Tim 3:15-16 NKJV