Ignatius of Antioch

None of these things is hid from you, if ye perfectly possess that faith and love towards Christ Jesus which are the beginning and the end of life. For the beginning is faith, and the end is love. Now these two, being inseparably connected together, are of God, while all other things which are requisite for a holy life follow after them. No man [truly] making a profession of faith sinneth; nor does he that possesses love hate any one. …

Epistle of Ignatius to the Ephesians ↗

Oecumenius

Little children, let no one deceive you. Whoever practices righteousness is righteous, just as He is righteous. But he proceeds more firmly with these words, saying: "let no one deceive you." For it cannot be otherwise than this: He who does righteousness knows the Righteous One, and is righteous, just as He is, that is, God.

Commentary on 1 John ↗

Augustine of Hippo

"Little children, let no man seduce you. He that doeth righteousness is righteous, as He is righteous." What, on hearing that we are "righteous as He is righteous," are we to think ourselves equal with God? Ye must know what means that "as:" thus he said a while ago, "Purifieth himself even as He is pure." Then is our purity like and equal to the purity of God, and our righteousness to God's righteousness? Who can say this? But the word "as," is not always wont to be used in the sense of equality. …

Ten Homilies on 1 John 4 ↗

Bede

Little children, let no one deceive you. Whoever practices righteousness is righteous, etc. And above: He purifies himself, it says, just as He is pure. Not that our righteousness or holiness can be equal to the divine, since it is written: There is none holy like the Lord (1 Samuel 2), but just as there is much difference between the face of a man and the image in a mirror, because the image is in imitation, the body in reality, and yet, just as here are eyes, so also there; yet the matter differs, but just as it pertains to …

Commentary on the Catholic Epistles ↗