Psalm 18:49
47 The one true God completely vindicates me; he makes nations submit to me. 48 He delivers me from my enemies. You snatch me away from those who attack me; you rescue me from violent men. 49 So I will give you thanks before the nations, O Lord. I will sing praises to you. 50 He gives his king magnificent victories; he is faithful to his chosen ruler, to David and his descendants forever.”
Romans 15:9
7 Receive one another, then, just as Christ also received you, to God’s glory. 8 For I tell you that Christ has become a servant of the circumcised on behalf of God’s truth to confirm the promises made to the fathers, 9 and thus the Gentiles glorify God for his mercy. As it is written, “Because of this I will confess you among the Gentiles, and I will sing praises to your name.” 10 And again it says: “Rejoice, O Gentiles, with his people.” 11 And again, “Praise the Lord all you Gentiles, and let all the peoples praise him.”
Notes and References
"... There is little consensus, but Hays’ messianic exegesis, which evokes the narrative of the psalm and locates Christ’s proclamation in the context of the Davidic Messiah, seems likely, providing, as Hays argues, a framework for reading the whole catena. Paul makes use of this psalm of thanksgiving, attributed to the Lord’s servant, David, by highlighting the psalmist’s confession of the Lord among the nations. ‘Therefore I will confess you among the Gentiles, and sing praises to your name.’ This first citation (Romans 15:9) is likely to be from Psalm 18:49 (LXX 7:50), although LXX 2 Samuel 22:50 is a possible source because of its similar wording. It is represented verbatim apart from the omission of the vocative κύριε, quite possibly, as Hays says, because it is the 'Lord' who speaks. Christ is the one who has welcomed Jew and Gentile, so it is quite possible that he himself is standing in the midst of the eschatological congregation, offering praise to God. Wagner sees Christ as the referent, but he also points out that Paul perceives his own ministry to be following that of Christ ..."
Whittle, Sarah Covenant Renewal and the Consecration of the Gentiles in Romans (pp. 136-137) Cambridge University Press, 2015