Why does the KJV add more to Matthew 19:9 vs other translations?

Question

I'm not sure if this is the right place to ask this, but Matthew 19:9 in the KJV reads:

And I say unto you, Whosoever shall put away his wife, except it be for fornication, and shall marry another, committeth adultery: and whoso marrieth her which is put away doth commit adultery.

Other translations, such as the ESV, simply read:

And I say to you: whoever divorces his wife, except for sexual immorality, and marries another, commits adultery.

Which translation is more accurate? Because the differences make a huge difference in how we should view any exceptions Jesus might have given on this subject.

The KJV would seem to make it to where, even in cases of unrepentant adultery, the innocent victim of an adulterous divorce is bound for life to singleness. But the ESV and other translations seem to allow for freedom for the victim.

Answer 1

The difference between the versions is due to the choice of underlying Greek text:

• the ESV, NIV, NASB and most modern versions follow the NA28 and UBS5 text.
• the KJV and NKJV follow the Textus Receptus which add an extra sentence, "And he who marries a divorced woman commits adultery"

Both translations are accurate but are based on different manuscript Greek texts and traditions. The extra sentence is far from uniform in the manuscripts.

The existence of this extra sentence is not so consequential as the OP suggests, as the same teaching is found in other places, such as Mark 10:11 and Matt 5:32 and was presumably copied from there, as the earliest manuscripts do not have it.

For the extensive details about which manuscripts support which reading, see UBS5 Greek text.

Answer 2

Bruce Metzger's textual commentary discusses the reason the committee decided on the textual reading for the Greek text usually used in modern translations while the KJV used the Textus Receptus. In summary the difference in the translations is due to textual differences in the Greek text.

   19:9      μὴ ἐπὶ πορνείᾳ καὶ γαμήσῃ ἄλλην μοιχᾶται {B}

The “excepting clause” in the Matthean account of Jesus’ teaching on divorce occurs in two forms: παρεκτὸς λόγου πορνείας (“except on the ground of unchastity”) and μὴ ἐπὶ πορνείᾳ (“except for unchastity”). It is probable that the witnesses (including B D f f 33) that have the former reading have been assimilated to 5:32, where the text is firm. Likewise the phrase ποιεῖ αὐτὴν μοιχευθῆναι (“makes her commit adultery” [i.e. when she remarries]) has come into several witnesses (including B C* f ) from 5:32, where it is firm. The short reading of 1574, καὶ γαμήσῃ ἄλλην, has been conformed to the prevailing text of Mk 10:11. -- Metzger, B. M., United Bible Societies. (1994). A textual commentary on the Greek New Testament, second edition a companion volume to the United Bible Societies’ Greek New Testament (4th rev. ed.) (p. 38). United Bible Societies.