Heaven and earth will pass away, but my words will never pass away.
Nothing on earth is perfect. Nothing on earth will last forever. You relate to eternity as being in heaven. Yet Jesus is saying here that heaven and earth could pass away but His Words will never go away. They will always be filled with power and grace.
Jesus came into the world not to condemn but to save. His objective was not to abolish the old covenant but to fulfill it. He is declaring here that although the old testament has passed; His Words will never pass. People in this time were confused and trying to sort out this Messiah speaking and doing great miracles. Continually in the first books of the new testament, the leaders "reasoned" within themselves trying to sort out His Words with the environment they were used to.
God is the same yesterday, today and forever. His Word will always be the same. It is your sure foundation to stand on. He healed in the old and new testament. He delivered in the old and new testament. He gave the power to get wealth in the old and new testament.
You are in a divine moment right now as you read these words. Jesus will never leave you and His Word will not be returned to Him void. It will accomplish exactly what He sent it to do. This includes His Word in your life. Rejoice for He has sent His Word!