LXX Psalm 17:50
47 It is God that avenges me, and has subdued the nations under me; 48 my deliverer from angry enemies: thou shalt set me on high above them that rise up against me: thou shalt deliver me from the unrighteous man. 49 Therefore will I confess to thee, O Lord, among the Gentiles, and sing to thy name. 50 God magnifies the deliverances of his king; and deals mercifully with David his anointed, and his seed, for ever.
Romans 1:2
1 From Paul, a slave of Christ Jesus, called to be an apostle, set apart for the gospel of God. 2 This gospel he promised beforehand through his prophets in the holy scriptures, 3 concerning his Son who was a descendant of David with reference to the flesh, 4 who was appointed the Son-of-God-in-power according to the Holy Spirit by the resurrection from the dead, Jesus Christ our Lord. 5 Through him we have received grace and our apostleship to bring about the obedience of faith among all the Gentiles on behalf of his name.
Notes and References
"... The third pre-text originates from a cluster of storytelling psalms, LXX Psalms 17, 88, and 131. While the larger contexts of each psalm contain varying points of emphases related to Israel's history, one common characteristic is that they ground the hope of the nation's deliverance in the prior promise of a Davidic descendant ..."
Crisler, Channing L. An Intertextual Commentary on Romans Volume 1 (p. 84) Pickwick Productions, 2021