A.T. Robertson Commentary Revelation 7:14

"And I say unto him, My lord, thou knowest. And he said to me, These are they that come of the great tribulation, and they washed their robes, and made them white in the blood of the Lamb." — Revelation 7:14 (ASV)

I say (ειρηκα). Perfect active indicative of ειπον, "I have said." "To the Seer's mind the whole scene was still fresh and vivid" (Swete) like κεκραγεν in Joh 1:15 and ειληφεν in Re 5:7, not the so-called "aoristic perfect" which even Moulton (Prol. p. 145) is disposed to admit.

My lord (Κυριε μου). "An address of reverence to a heavenly being" (Vincent), not an act of worship on John's part.

Thou knowest (συ οιδας). "At once a confession of ignorance, and an appeal for information" (Swete), not of full confidence like συ οιδας in Joh 21:15f..

They which come out of the great tribulation (ο ερχομενο εκ της θλιψεως της μεγαλης). Present middle participle with the idea of continued repetition. "The martyrs are still arriving from the scene of the great tribulation" (Charles). Apparently some great crisis is contemplated (Matthew 13:19ff.; 24:21), though the whole series may be in mind and so may anticipate final judgment.

And they washed (κα επλυναν). First aorist active indicative of πλυνω, old verb, to wash, in N.T. only Lu 5:2; Revelation 7:14; 22:14. This change of construction after ο ερχομενο from ο πλυνησαντες to κα επλυναν is common in the Apocalypse, one of Charles's Hebraisms, like κα εποιησεν in 1:6 and κα πλανα in 2:20.

Made them white (ελευκαναν). First aorist active indicative of λευκαινω, to whiten, old verb from λευκος (verse 13), in N.T. only here and Mr 9:3. "Milligan remarks that robes are the expression of character and compares the word habit used of dress" (Vincent). The language here comes partly from Ge 49:11 and partly from Ex 19:10,14. For the cleansing power of Christ's blood see also Ro 3:25; 5:9; Colossians 1:20: Ephesians 1:7; 1 Peter 1:2; Hebrews 9:14; 1 John 1:7; Revelation 1:5; 5:9; 22:14. "The aorists look back to the life on earth when the cleansing was effected" (Swete). See Php 2:12f. for both divine and human aspects of salvation.

In the blood of the Lamb (εν τω αιματ του αρνιου). There is power alone in the blood of Christ to cleanse from sin (1 John 1:7), not in the blood of the martyrs themselves. The result is "white," not "red," as one might imagine.