ναί, a particle of assertion or confirmation (akin to 
νή; cf. Donaldson, Cratylus § 189), from 
Homer down, 
yea, verily, truly, assuredly, even so: 
Matthew 11:26; 
Luke 10:21; 
Philemon 1:20; 
Revelation 1:7; 
Revelation 16:7; 
Revelation 22:20; 
ναί, 
λέγω ὑμῖν κτλ., 
Matthew 11:9; 
Luke 7:26; 
Luke 11:51; 
Luke 12:5; 
ναί, 
λέγει τό πνεῦμα, 
Revelation 14:13; it is responsive and confirmatory of the substance of some question or statement: 
Matthew 9:28; 
Matthew 13:51; 
Matthew 15:27; 
Matthew 17:25; 
Matthew 21:16; 
Mark 7:28; 
John 11:27; 
John 21:15; 
Acts 5:8 (
Acts 5:9); 
Acts 22:27; 
Romans 3:29; a repeated 
ναί, 
most assuredly (
A. V. yea, yea), expresses emphatic assertion, 
Matthew 5:37; 
ἤτω ὑμῶν τό ναί ναί, let your 
ναί be 
ναί, i. e. let your allegation be true, 
James 5:12 (
Buttmann, 163 (142); 
Winer's Grammar, 59 (58)); 
εἶναι or 
γίνεσθαι ναί καί οὐ, to be or show oneself double-tongued, i. e. faithless, wavering, false, 
2 Corinthians 1:18f; 
ἵνα παῥ ἐμοί τό ναί ναί καί τό οὐ οὐ, that with me should be found both a solemn affirmation and a most emphatic denial, i. e. that I so form my resolves as, at the dictate of pleasure or profit, not to carry them out, ibid. 17 (cf. 
Winer's Grammar, 460 (429)); 
ναί ἐν αὐτῷ γέγονεν, in him what was promised has come to pass, 
2 Corinthians 1:19; 
ἐπαγγελίαι ἐν αὐτῷ τό ναί namely, 
γεγόνασιν, have been fulfilled, have been confirmed by the event, 
2 Corinthians 1:20 (cf. Meyer at the passage). It is a particle of appeal or entreaty, like the (English 
yea) (German 
ja): with an imperative, 
ναί... 
συλλαμβάνου αὐταῖς, 
Philippians 4:3 (where 
Rec. has 
καί for 
ναί); 
ναί ἔρχου, 
Revelation 22:20 Rec.; so 
ναί ναί, Judith 9:12. (A classification of the uses of 
ναί in the N. T. is given by Ellicott on 
Philippians 4:3; cf. 
Green, 'Grit. Note' on 
Matthew 11:26.) 
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