5 And that we may more fully understand, beloved brethren, that patience is a thing of God, and that whoever is gentle, and patient, and meek, is an imitator of God the Father; when the Lord in His Gospel was giving precepts for salvation, and, bringing forth divine warnings, was instructing His disciples to perfection, He laid it down, and said, “You have heard that it is said, You shall love your neighbour, and have your enemy in hatred. But I say unto you, Love your enemies, and pray for them which persecute you; that you may be the children of your Father which is in heaven, who makes His sun to rise on the good and on the evil, and rains upon the just and on the unjust.
For if you love them which love you, what reward shall you have? Do not even the publicans the same? And if you shall salute your brethren only, what do you do more (than others)? Do not even the heathens the same thing? Be therefore perfect, even as your Father in heaven is perfect.” He said that the children of God would thus become perfect. He showed that they were thus completed, and taught that they were restored by a heavenly birth, if the patience of God our Father dwell in us— if the divine likeness, which Adam had lost by sin, be manifested and shine in our actions. What a glory is it to become like to God! What and how great a felicity, to possess among our virtues, that which may be placed on the level of divine praises!
Source: The Treatises of Cyprian (New Advent)