Romans 12:7

εἴτε διακονίαν κ.τ.λ. Sc. ὦμεν; cf. 1 Timothy 4:15, ἐν τούτοις ἴσθι; so with the next two clauses, thoroughness and devotion are insisted upon.

διακονίαν. The widest word for service, including the functions of apostles, prophets, etc., but here probably of personal service in the community; cf. Phoebe Romans 16:1. ἐν τῇ διακ., the special way of serving given to each.

ὁ διδάσκων. The change of form probably merely the result of instinctive literary feeling. The teacher is distinguished from the prophet (Acts 13:1; 1 Corinthians 12:28; Ephesians 4:11) perhaps as expounding, elucidating and systematically imparting truth rather than discovering and declaring it. It is of course a distinction of functions not of persons. See above, Romans 12:6.

ἐν τῇ διδασκαλίᾳ. Cf. 1 Timothy 4:13; 1 Timothy 4:16. The act or practice of teaching, not the thing taught (so generally in the Pastoral Epp.).