Why is the phrase ‘not being myself under the law’ missing in 1 Corinthians 9:20 in the KJV?

This parenthetical statement, “though not myself being under the law” can be seen in newer translations of the Bible. The King James Version used the Textus Receptus as the basis for its translation.

Remember that the KJV was translated in 1611, using the best Greek manuscript evidence we had at the time. But in the last 400 or so years, many more Greek manuscripts, and some older ones than the ones they had in 1611, have been found.

Newer translations of the Bible have access to these older manuscripts. The general rule is that the older the manuscript, the more accurate to the original Greek manuscripts. The more accurate, the better reading we have of those originals.

So a lot of the newer versions not only call into question some of the phrases and passages we have from the KJV, like the ending of Mark and the story of the adulterous woman in John 7-8, but produce what we believe to be closer readings to the original manuscripts.

This is an earlier reading from older manuscripts and what they had when they translated the KJV. Therefore, it has been added into the text as a parenthetical. Renowned Greek manuscript scholars like Bruce Metzger suggest that the text was there, but the copyist’s eye passed over it, flowing from one line to the next on the manuscript.