John Gill

Heaven and earth shall pass away,.... Which may be understood either affirmatively, as what will be at the second coming of Christ; or comparatively, rather than any thing said by Christ should; and so shows the certainty and irreversibleness of his predictions, as it follows: but my words shall not pass away; which is true of all the words of Christ he ever spake, and here particularly relates to those he had just delivered, concerning the calamities that should come upon the Jewish nation; See Gill on Mat 24:35.