These quotes about righteousness are given to help us determine the proper interpretation of the Greek words related to δικαιω. This word is the verb form of a word translated as to justify, to make righteous, and to free. The noun is translated as righteousness, right standing with God, and justification. The meaning of the word is in dispute between Protestants and catholics (which I write in small letters to include the Roman Catholics and the various branches of Orthodox churches) and among Protestant denominations as well.
Because aid in translating δικαιω and cognates is the purpose of this page, all the quotes are from early Christian writers who wrote in Greek. No "Latin Fathers" are included on this page.
First Clement is a letter written from the Church at Rome to the Church at Corinth. It is nowhere said to have been written by Clement, but later writers univerally attribute the letter to him.
Every kind of honor and happiness was bestowed upon you [Corinthians after you repented at Paul's letters to you]. And then was fulfilled that which was written, "My beloved ate and drank, was enlarged and became fat, and kicked" [Deut. 32:15]. From there flowed jealousy and envy, strife and sedition, persecution and disorder, war and captivity. So the worthless rose up against the honored, those of no reputation against such as were renowned, the foolish against the wise, and the young against those advanced in years. For this reason righteousness and peace are now departed far from you, inasmuch as everyone abandons the fear of God and has become blind in their faith. Nor do they walk in the ordinances of his appointment [i.e., the offices in the church] nor behaves in a way fitting for a Christian. Instead, they walk after their own wicked lusts, resuming the practice of an unrighteous and ungodly envy ... (1 Clement 3)
Let us steadily contemplate those who have perfectly served His Excellent Glory. Let us take Enoch who, being found righteous in obedience, was translated and death was never known to have happened to him. [ed. note: Note the careful wording Clement uses.] (1 Clement 4)
Abraham believed God, and it was accounted to him as righteousness [Gen. 15:5-6; Rom. 4:3; Jam. 2:23]. Because of his faith and hospitality, a son was given to him in his old age and, in the exercise of obedience, he offered to him as a sacrifice to God on one of the mountains which [God] showed him. (1 Clement 10)
Therefore, brothers, let us be of humble mind, laying aside all haughtiness, pride, foolishness, and angry feelings. Let us act according to what is written, for the Holy Spirit say, "Do not let the wise man boast in his wisdom, nor let the mighty man boasts in his might, nor let the rich man boast in his riches, but let the one who boasts boast in this, in diligently seeking him and doing judgment and righteousness" [Jer. 9:23, not quoted accurately]. [Let us] be especially mindful of the words of the Lord Jesus which he spoke, teaching us meekness and patience. (1 Clement 13)
Let testimony to our good deeds be borne by others, as it was in the case of our righteous forefathers. Boldness, arrogance, and audacity belong to those that are accursed of God, but moderation, humility, and gentleness to such as are blessed by him. (1 Clement 30)
[The long list of holy men I just gave you] were all highly honored and made great, not for their own sake or for their own works or for the righteousness which they have done, but through the operation of his will. We too, being called by his will in Christ Jesus, are not justified by ourselves, nor by our own wisdom, understanding, godliness, or works which we have done in holiness of heart, but by that faith through which, from the beginning, Almighty God has justified all men. (1 Clement 32)
We see then how all righteous men have been adorned with good works and how the Lord himself, adorning himself with his works, rejoiced. Therefore, having such an example, let us give in to his will without delay, and let us work the work of righteousness with all our strength. (1 Clement 33)