Lk 17:7-10
At that time the Lord said, ‘Which of you, with a servant ploughing or minding sheep, would say to him when he returned from the fields, “Come and have your meal at once”? Would he not be more likely to say, “Get my supper ready; fasten your belt and wait on me while I eat and drink. You yourself can eat and drink afterwards”? Must he be grateful to the servant for doing what he was told? So with you: when you have done all you have been told to do, say, “We are useless servants: we have done no more than our duty”.