In this sermon the writer of Hebrews tells us to remember those who taught us the Word of God. Remembering shows action and it is an active recall of the proper doctrine that has been placed within us for over 2000 years that we need to remember. The reason that we have a solid Christian faith today is because of the faithfulness of the preachers and teachers who have gone before us.
This keeps us grounded in the Word and keeps us from blowing to and fro after unsound doctrine.