For there are certainly souls who are joyfully and with a good conscience awaiting the judgment of Christ; for they are in the rank and fellowship of those who believe in Christ, and who show fruits of faith through charity and beneficence toward the poor, or through patience in suffering with them. For, as I have said, he who does not have faith will not do works of mercy to Christians, but he who does them, will do them because he believes that he has a faithful Savior and redeemer in Christ, who has reconciled him to God. Therefore he must have also a kind, loving heart toward his neighbors, even toward his enemies, and serve them in every time of need. Yea, he endures also, as I have just said, those things which come upon him from the world and the devil on account of his faith.
Whosoever is thus minded, I say, let him be joyful and of good courage; for he has already the blessed and joyful verdict: come, thou blessed one, for thou hast also been one of the least of my brethren, who has thyself suffered hunger and thirst, or who hast served the other hungry and thirsty ones, and hast shown mercy, as I have done.” 
 John Nicholas Lenker ed. and trans, Sermons of Martin Luther, (Grand Rapids, MI: Baker Book House, 1983), vol 5:379-395.