Pray for them which despitefully use you. Jesus himself, on his cross, when he prayed that his murderers might be forgiven, for they knew not what they were doing, and his true servant Stephen, who copied faithfully his Lord in his own dying moments, are beautiful though extreme examples of what is meant here.
It is St. Luke alone who mentions this act of Jesus on the cross; it is St. Luke, again, who has preserved St. Stephen's words, uttered while they were stoning him to death. He would show how the Lord's command could be carried out.