17:7-10 What is this parable called and what does it teach?

This is called the parable of unprofitable servants. It is also known as the parable of the servant's reward; the unworthy slave; the farmer and servant, etc. This parable answers two questions: what is the obligation of a disciple toward Christ, and what attitude should a disciple have while serving Christ?

Jesus told this parable to give His disciples a perspective on the meaning of servanthood. In doing what is required, a servant is not doing anything creditworthy, deserving of his master's thanks, he is simply fulfilling his duty. Christians also, in fulfilling their obligations to God should not expect any special rewards either. All that we can do as servants of God is merely our common duty.

We merit nothing, and should not expect anything for what we do. This clearly teaches against the attitude of the elder son toward his father in the parable of the lost son (cp Lk 15:25-32).