This Bible contradiction is from the Skeptic's Annotated Bible.
Matthew 10:23 View context
But when they persecute you in this city, flee ye into another: for verily I say unto you, Ye shall not have gone over the cities of Israel, till the Son of man be come.
Matthew 24:14 View context
And this gospel of the kingdom shall be preached in all the world for a witness unto all nations; and then shall the end come.