Romans 13:8

εἰ μὴ τὸ ἀλλήλους ἀγαπᾷν = except mutual love. This is the debitum immortale of Bengel; hoc enim et quotidie solvere et semper debere expedit nobis (Origen). ὁ γὰρ ἀγαπῶν τὸν ἕτερον : he who loves his neighbour, the other with whom he has to do. Cf. Romans 2:1; Romans 2:21 (Weiss). νόμον πεπλήρωκεν = has done all that law requires. From what follows it is clear that Paul is thinking of the Mosaic law; it was virtually the only thing in the world to which he could apply the word νόμος, or which he could use to illustrate that word. The relation of chaps. 12 and 13 to the Gospels makes it very credible that Paul had here in his mind the words of our Lord in Matthew 22:34 ff.