Does he thank the servant because he did what was commanded?

"Will any one of you who has a servant plowing or keeping sheep say to him when he has come in from the field, 'Come at once and recline at table'? Will he not rather say to him, 'Prepare supper for me, and dress properly, and serve me while I eat and drink, and afterward you will eat and drink'? Does he thank the servant because he did what was commanded? 10 So you also, when you have done all that you were commanded, say, 'We are unworthy servants; we have only done what was our duty.'"
Luke 17:7-10 (ESV)
 
"We used to be roused and stirred by the clarion call of duty, as well as soothed and comforted by the tender breathings of love. And here the call comes to us loud and clear, waxing even louder as we listen and reflect. ‘Do your duty; and when you have done it, however laborious and painful it may be, remember that you have only done your duty. Do not give yourselves airs of complacency, as though you had achieved some great thing. Do not give yourselves air of martyrdom as though some strange thing had happened to you. Neither pity yourselves, nor plume yourselves on what you have done or borne. Do not think of yourselves at all, but of God, and of the duties you owe to Him. That you have done your duty—let this be your comfort, if at least you can honestly take it. And if you are tempted to a dainty and effeminate self-pity for the hardships you have borne, or to a dangerous and degrading self-admiration for the achievements you have wrought, let this be your safeguard, that you have done no more than your duty.’ It is in this strain that our Lord speaks to us here." (S. Cox, D. D.)