Mark 13:5 - Ellicott's Commentary On The Whole Bible

And Jesus answering them began to say. — The report which follows, common as it is to the first three Gospels, serves as an admirable example of the extent of variation compatible with substantial accuracy, and with the recognition of an inspired guidance as ensuring that accuracy. The discourse obviously made a deep impression on those who heard it, as afterwards on those to whom they repeated it, and so it passed from mouth to mouth, but probably it was not committed to writing till the events which it foretold came within the horizon. On all points common to the three records, see Notes on Matthew 24.