John 5:3-4 KJV
³In these lay a great multitude of impotent folk, of blind, halt, withered, waiting for the moving of the water. ⁴For an angel went down at a certain season into the pool, and troubled the water: whosoever then first after the troubling of the water stepped in was made whole of whatsoever disease he had.
In the Revised Version is not only verse 4 omitted, but also the end of verse 3
S. John 5:3 RV1895
In these lay a multitude of them that were sick, blind, halt, withered.
In the New American Standard Bible the text is put between brackets, with a footnote that these words are not found in the early manuscripts.
John 5:3-4 NASB
³In these lay a multitude of those who were sick, blind, lame, and withered, [waiting for the moving of the waters; ⁴for an angel of the Lord went down at certain seasons into the pool and stirred up the water; whoever then first, after the stirring up of the water, stepped in was made well from whatever disease with which he was afflicted.]
The reason for this is, that it is considered unlikely that these words were in the original text of the Gospel, as they are lacking in the “earliest and best witnesses”; And several ancient Greek manuscripts that do contain them, enclose them with markings indicating doubts about their authenticity.
The passage contains words or expressions that appear nowhere else in John (such as the Greek words for “at a certain season [= occasionally]” and “stirring” and “diseases”), and the manuscripts that contain this verse differ among themselves as to the wording.
The UBS text gave the omission of this verse a confidence rating of A.
This verse was omitted from Edward Harwood’s Greek NT (1776), marked as doubtful in Griesbach’s editions (1777), and thereafter generally relegated to a footnote, enclosed in brackets, or omitted completely.
Henry Alford wrote, “The spuriousness of this controverted passage can hardly be questioned.”
Without the words at issue the context simply states that a swimming or bathing pool in or near Jerusalem was a gathering place for sick and crippled people, some of whom sought to get into the pool (either for physical comfort or for ritual cleansing) and it was there that Jesus performed a miraculous healing.
But the words quoted above complicate this story by asserting that miraculous cures were already taking place at this pool in the absence of Jesus, owing to the unpredictable intervention of an (apparently invisible) angel.
This passage in John 5 is the only mention of this pool – no such miraculous pool is mentioned in Josephus or other histories.
The words in question do not appear in the oldest manuscripts, and in those manuscripts that contain them they are sometimes marked as doubtful, and differ from manuscript to manuscript “with that extreme variation in the reading which so often indicates grounds for suspicion”.
The italicized words do not appear at all in Papyrus 66, 75, and some Italic, Syriac, Coptic, and Latin Vulgate manuscripts, and in quotations of the story by several early Greek Fathers.
Verse 4 (“For an angel …”) appears in some without the concluding words of verse 3 (‘waiting for the stirring of the water …”) in one manuscript it says that the angel “bathed in the water” rather than “descended into the water”.
The concluding words of verse 3 but not any of verse 4 appear in a manuscript from the ninth century, and some Latin manuscripts.
Some manuscripts contain the words enclosed by marks of doubt.
Among the manuscripts that contain this sentence-and-a-half, there are many variations and permutations.
The Revised Version (1881) omitted the italicized words from its main text, making the passage read: “… a multitude of them that were sick, blind, halt, withered.  And a certain man was there …”, and as a side-note, “Many ancient authorities insert, wholly or in part,” and here present the italicized words exactly as they appeared in the KJV.
Several modern versions similarly relegate those words to a footnote, and some others (such as Moffatt) include the words in the main text but enclosed in brackets with an explanation in a footnote.