Verse 10 contains the key to increased faith: the word "say." The principle boils down to working with a specific attitude. Christ tells us to do everything possible to be as profitable as this servant (verses 7-8), without expecting any recognition for it (verse 9). Then we can present the sincere, humble attitude: "We are unprofitable servants. We have done what was our duty to do."
Humanly, the servant could have taken the attitude, "You owe me! Didn't I go 'above and beyond'?" No! "Above and beyond" is not applicable to our relationship with God. We could never do enough to put God in our debt.
I Corinthians 4:7 asks, "What do you have that you did not receive?" We have no room to boast that we have done anything without God's oversight (Daniel 4:28-35). I Corinthians 6:20 tells us we owe God everything, as He has redeemed us by the most precious blood of His own Son. Paul commands us not to grow weary but do good to all (Galatians 6:9-10). James echoes him: "Therefore, to him who knows to do good and does not do it, to him it is sin" (James 4:17). God has backed us into a corner. Where do we have any room for "above and beyond"?
In both the planning and action stages of works of goodness or faith, we decide how much to give, how far to go. But in hindsight, what good thing have we ever done that qualifies for "above and beyond" our duty to God? Whatever it was, the Scriptures plainly show we were commanded to do it! It was our duty because we found it in our power to do it (Proverbs 3:27). We cannot take the attitude that, "We did these good things, so that makes us profitable to God." If we do, we have no basis for faith. Our faith would be in ourselves, not in God.