Working together with him ( συνεργουντες ). We are co-workers, partners with God (1Co 3:9), in this work of grace.

In vain ( εις κενον ). Into emptiness. The plan of God, the work of Christ on the Cross, the pleas of the ambassador may all be nullified by the recipient of the message.

Behold, now is the acceptable time ( ιδου νυν καιρος ευπροσδεκτος ). Here is another "Pauline parenthesis" (Plummer) as in 5:7 by the quotation from Isa 49:8. The LXX has  δεκτος ( δεκτο ) verbal of  δεχομα, but Paul employs the double compound ( ευ, προσ, δεκτος ), well-received. It occurs in Aristophanes, Plutarch, inscription, etc.

Giving no occasion of stumbling in any thing ( μηδεμιαν εν μηδεν διδοντες προσκοπην ).  Προσκοπη, late word (Polybius, LXX), from  προσκοπτω, to strike against, to stumble. Only here in N.T. Note double negative in the Greek.

That the ministry be not blamed ( ινα μη μωμηθη η διακονια ). Negative purpose ( ινα μη ). First aorist passive subjunctive of old verb  μωμαομα from  μωμος, blot, blemish. One can read with profit J. A. Hutton's Warrack Lectures, That the Ministry Be Not Blamed.

But in everything commending ourselves ( αλλ' εν παντ συνιστανοντες εαυτους ). Paul gives a marvellous summary of his argument about the dignity and glory of ministers of Christ as

ministers of God ( ως θεου διακονο ) under three aspects, the first with

in ( εν ) verses 3-7a, the second with

by ( δια ) verses 7b,8, the third with

as ( ως ) verses 9-10. The negative view with  εν we have in verse 3, then the positive in verses 4-7a. Each word carries a story that can be filled in from Paul's own life as a preacher with an echo in that of us all.

In distresses ( εν στενοχωριαις ). In tight places (12:10). Late word from  στενοχωρεω (see on 4:8).

In stripes ( εν πληγαις ). In blows, wounds (Lu 10:30; 12:48; Ac 16:23,33). Our plague.

In tumults ( εν ακαταστασιαις ). See on 1Co 14:33). Instabilities, often from politics.

In watchings ( εν αγρυπνιαις ). In sleeplessnesses, instances of insomnia. Old word, in N.T. only here and 11:27. Paul knew all about this.

In love unfeigned ( εν αγαπη ανυποκριτω ). Late and rare word ( α privative and  υποκριτος, from  υποκρινομα ) This is the only love that is worth while (Ro 12:9).

On the right hand and on the left ( των δεξιων κα αριστερων ). Offensive weapons ( οπλων ) on the right, defensive on the left. See 1Th 5:8; Eph 6:11 for Paul's description of the panoply of God and Ro 6:13 for the phrase "weapons of righteousness," the only kind that will stand the strain. See also Book of Wisdom 5:18ff.

By glory and dishonour ( δια δοξης κα ατιμιας ). Here  δια is no longer instrument, but state or condition.  Δοξα here is glory. See Ro 9:21; 2Ti 2:20 for contrast between honour and dishonour ( τιμη, ατιμια ).

By evil report and good report ( δια δυσφημιας κα ευφημιας ). Play on the words with prefixes  δυσ- and  ευ- and  φημη.  Δυσφημια is a late word, only here in N.T.  Ευφημια, old and common word, only here in N.T.

As deceivers and yet true ( ως πλανο κα αληθεις ). Paul takes up  ως now in place of  δια which succeeded  εν. Note use of  κα in sense of "and yet" (adversative).  Πλανος is late word (Diodorus, Josephus) for wandering, vagabond, impostor (cf.  πλαναω, to lead astray, used of Christ, Joh 7:12). In N.T. only here; Mt 27:63 (of Christ by Pharisees); 2Jo 1:7. "In the Clementines St. Paul is expressly described by his adversaries as  πλανος and as disseminating deceit ( πλανην )" (Bernard). Such slander from one's enemies is praise.

As unknown and yet well known ( ως αγνοουμενο κα επιγινοσκομενο ). "As ignored (as nonentities, obscure, without proper credentials 3:2) and yet fully recognized (by all who really matter as in 11:6)."

And behold, we live ( κα ιδου ζωμεν ). Cf. the hazards of his life (1:8; 4:10; 11:23). His whole career is full of paradox).

Always rejoicing ( αε χαιροντες ). Even in sorrow (11:9; 1Th 5:16; Ro 5:3-5; 9:2; Php 2:18,27; 3:1; 4:4,15).

Yet making many rich ( πολλους δε πλουτιζοντες ). Old word from  πλουτος (wealth), to enrich. Spiritual riches Paul has in mind as in 1Co 1:5 (cf. Mt 5:37).

As having nothing and yet possessing all things ( ως μηδεν εχοντες κα παντα κατεχοντες ). Contrast between  μηδεν (nothing) and  παντα (all things, cf. 1Co 3:22) and  εχω (to have) and  κατεχω (to hold down, to hold fast). Play on words (simple and compound) as in 3:2; 4:8. Climax of Paul's panegyric on the Christian ministry. He now resumes the thread of the story broken off in 2:14.

Our mouth is open unto you ( το στομα ημων ανεωιγεν προς υμας ). Second perfect active indicative of  ανοιγω and intransitive, stand open. He has kept back nothing in his portrayal of the glory of the ministry as the picture of the open mouth shows.

Our heart is enlarged ( η καρδια ημων πεπλατυντα ). Perfect passive indicative of old verb  πλατυνω, to broaden, from  πλατυς, broad. In N T. only here and Mt 23:5 (cf. phylacteries). Hence his freedom of speech for "out of the abundance of the heart the mouth speaks" (Mt 12:34).

Ye are not straitened in us ( ου στενοχωρεισθε εν ημιν ). The same figure as in verse 11. See on 4:8 for  στενοχωρεω. There is no restraint in me (my heart). My adversaries may have caused some of you to tighten up your affections ( σπλαγχνα for affection as in Jas 5:11; 1Pe 3:8).

Now for a recompense in like kind ( την δε αυτην αντιμισθιαν ). No example of this expressive word outside of this passage and Ro 1:27 and later Christian writers. Paul may have found it in use in the Koine vernacular or he may have coined it from  αντιμισθος, remunerating (paying back). There is no verb here to explain the accusative which may be the accusative of general reference or the object of a verb not expressed.

Be ye also enlarged ( πλατυνθητε κα υμεις ). As I have been (verse 11). First aorist passive imperative of  πλατυνω.

Be not unequally yoked with unbelievers ( μη γινεσθε ετεροζυγουντες απιστοις ). No other example of this verb has yet been found, though the adjective from which it is apparently formed,  ετεροζυγος (yoked with a different yoke) occurs in Le 19:19 of the union of beasts of different kinds. In De 22:10 we read: "Thou shalt not plough with an ox and an ass together." Literally, "Stop becoming ( μη γινεσθε present imperative, not  μη γενησθε aorist subj.) unequally yoked with unconverted heathen (unbelievers)." Some were already guilty. Marriage is certainly included, but other unions may be in mind. Cf. Eph 5:7. Paul gives as the reason ( γαρ ) for this prohibition five words in questions to distinguish the contrasts.

Fellowship ( μετοχη ). Sharing with and followed by associative instrumental case of  δικαιοσυνη (righteousness) and iniquity ( ανομια ). A pertinent challenge today when church members wink at violations of laws of the land and laws of God.

Communion ( κοινωνια ). Partnership to light ( φωτ dative case) with ( προς ), facing darkness.

Concord ( συμφωνησις ). Symphony. Late word from  συμφωνεω, only here and ecclesiastical writers, though  συμφωνημα in the papyri.

Belial ( Βελιαλ ). Transliteration of Hebrew word for worthlessness and applied to Satan (Book of Jubilees 1.20) as here. Paul graphically sums up the contrast between Christ and Belial (Satan), the heads of the contending forces of good and evil.

Portion ( μερις ). The fourth of the words. Here by "unbeliever" ( απιστου ) Paul means "disbeliever," not just an unconverted man who yet approves Christ.

Agreement ( συνκαταθεσις ). Fifth of these words. Late word, but common, though here only in N.T. Approved by putting together the votes. In the papyri  εκ συνκαταθεσεως means "by agreement." On the temple of God and idols see 1Co 10:14-22. See Lu 23:51 for the verb  συνκατατιθημ.

For we are the temple of the living God ( ημεις γαρ ναος θεου εσμεν ζωντος ). We, not temples (Ac 7:48; 17:24; 1Co 3:16; 6:19).

As God said ( καθως ειπεν ο θεος ). A paraphrase and catena of quotations, what J. Rendel Harris calls Testimonia (from Le 26:11f.; Isa 52:11; Eze 20:34; 37:27; 2Sa 7:8,14). Plummer notes that at the beginning "I will dwell in them" ( ενοικησω εν αυτοις ) is not in any of them. "As God said" points to Le 26:12; Eze 37:27.

Saith the Lord ( λεγε Κυριος ). Isa 52:5; Eze 20:33. Cf. Re 18:4.

Unclean thing ( ακαθαρτου ). Or unclean person. Genitive case is the same for both.

Saith the Lord Almighty ( λεγε Κυριος παντοκρατωρ ). 2Sa 7:8. This use of  εις is a Hebraism for Hebrew le instead of predicate nominative.  Παντοκρατωρ ( πασ, κρατεω, Ruler of all) is common in the LXX. Occurs also in the inscriptions and papyri. In the N.T. only here and in Revelation.