I cannot understand how any Christian can possibly have a close relationship with God in prayer and worship as long as he is robbing God in tithes and offerings. The only way to avoid deaf ears or resentful heart is to make sure that we have given ourselves to the Lord first. And there is, of course, from this parable a 4th principle. Servants always must give account to themselves. Now that's not a new thought to any of us.
Life is built that way.
When you go to school, you get report cards. When you are at work, you have a job review. All of us on your ministry staff have evaluations of our work from time to time. Everybody is accustomed to that. It is so boldly printed in the parable in verse 19.