Luke 17:6 So the Lord said, “If you have faith as a mustard seed, you can say to this mulberry tree, ‘Be pulled up by the roots and be planted in the sea,’ and it would obey you.
Jesus in response to the request of His disciples to increase their faith in dealing with offenses made it clear that if they had the smallest amount or measure of true faith (seed), nothing would be too hard to accomplish. In other words, “If you have any real faith at all, you will be able to win the victory over yourselves and be to others what they need from you”
The issue is not more faith but growing in faith by utilizing the already existing faith that was once for all delivered to the saints. With Jesus, they did not need more faith to BELIEVE, only assurance they had enough faith to LIVE and live out the impossible for “…the just shall live by faith” (Rom 1:17). This is working faith or faith that works. To polish on faith, He gave them an example of a humble, obedient servant/slave serving his master, fulfilling his duties not to gain rewards but to demonstrate that faith is more about faithfulness to the master and not the other way round. Faith matures as we become faithful with what we already have.