I’ve heard N.T. Wright suggest on more than one occasion that Paul is doing a play on words in Romans 2:29 when he says “…a person is a Jew who is one inwardly, and real circumcision is a matter of the heart—it is spiritual and not literal. Such a person receives praise not from others but from God.” This is suggested because “praise” (Gk. ὁ ἔπαινος) is meant to drawl the hearer’s attention (at least some of them) to name from which Jews derive their identity, the tribe of Judah (יהודה), which means “praise.” In other words, one who is a “Jew” (those who praise) receives his/her praise from God, not other people.
I found a footnote from Leon Morris that states the position more fully. 
Käsemann’s point that the Roman audience wouldn’t have understood Paul’s play on words is a valid criticism, but Paul may not have cared if everyone understood him. He may have wanted a few of his fellow Jews to understand his message.
 Leon Morris, The Epistle to the Romans (PNTC; Grand Rapids: Eerdmans, 1988), 142. Fn. 168. Screen shots from Google Books.