If we love our enemies and do good, we will be greatly rewarded  -  Luke 6:35

But love ye your enemies, and do good, and lend, hoping for nothing again; and your reward shall be great, and ye shall be the children of the Highest: for he is kind unto the unthankful and to the evil.

This behavior is exclusively shown by Christians, because they are the children of God. Those who are born of God – 1) love and do good to those who hate us and attempt to do us harm, 2) lend to them, whatever they ask, without expecting anything in return, 3) are kind to those who take advantage of us.