en_tn/rom/15/09.md

in order to confirm the promises ... and for the Gentiles to glorify God for his mercy

These are the two purposes for which Christ became a servant of the circumcision. Alternate translation: "in order to confirm the promises ... and in order that the Gentiles might glorify God for his mercy"

As it is written

You can translate this in an active form. Alternate translation: "as someone has written in the Scriptures" (See: rc://en/ta/man/translate/figs-activepassive)

sing praise to your name

Here "your name" is a metonym that refers to God. Alternate translation: "sing praise to you" (See: rc://en/ta/man/translate/figs-metonymy)