A.T. Robertson Commentary 2 Corinthians 3:1

"Are we beginning again to commend ourselves? or need we, as do some, epistles of commendation to you or from you?" — 2 Corinthians 3:1 (ASV)

To commend ourselves? (εαυτους συνιστανειν?). Late (Koine) form of συνιστημ, to place one with another, to introduce, to commend. Paul is sensitive over praising himself, though his enemies compelled him to do it.

Epistles of commendation (συστατικων επιστολων). Late verbal adjective from συνιστημ and often in the papyri and in just this sense. In the genitive case here after χρηιζομεν. Such letters were common as seen in the papyri (Deissmann, Light from the Ancient East, p. 226). N.T. examples of commending individuals by letters occur in Ac 15:25f.; 18:27 (Apollos), 1 Corinthians 16:10f. (Timothy); Romans 16:1 (Phoebe with the verb συνιστημ); Colossians 4:10 (Mark); 2 Corinthians 8:22f. (Titus and his companion).