Mark 7:16 KJV
If any man have ears to hear, let him hear.
The New American Standard Bible puts this verse between brackets and has a footnote saying that the early manuscripts do not contain this verse.
Mark 7:16 NASB
[If anyone has ears to hear, let him hear.]
The Revised Version omits this verse, but has a marginal note saying: “Many ancient authorities add verse 16” followed by the text of the verse
Besides the fact that the early manuscripts do not contain this verse, a secondary reason for omission may be that this verse is nearly identical with the verses in Mark 4:9 and Mark 4:23.
As said, this verse is lacking in early manuscripts, it is also lacking in some Coptic manuscripts.
But it is included in manuscripts only slightly less ancient, Italic manuscripts, the Vulgate, and some other ancient versions.
As it is missing in the oldest resources, and yet is identical to verses that remain, many editors seem confident in omitting its appearance here.