17 To these rewards that you also may come who had been possessed with jealousy and rancour, cast away all that malice wherewith you were before held fast, and be reformed to the way of eternal life in the footsteps of salvation. Tear out from your breast thorns and thistles, that the Lord's seed may enrich you with a fertile produce, that the divine and spiritual cornfield may abound to the plentifulness of a fruitful harvest. Cast out the poison of gall, cast out the virus of discords.
Let the mind which the malice of the serpent had infected be purged; let all bitterness which had settled within be softened by the sweetness of Christ. If you take both meat and drink from the sacrament of the cross, let the wood which at Mara availed in a figure for sweetening the taste, avail to you in in reality for soothing your softened breast; and you shall not strive for a medicine for your increasing health. Be cured by that whereby you had been wounded. Love those whom you previously had hated; favour those whom you envied with unjust disparagements.
Imitate good men, if you are able to follow them; but it you are not able to follow them, at least rejoice with them, and congratulate those who are better than you. Make yourself a sharer with them in united love; make yourself their associate in the alliance of charity and the bond of brotherhood. Your debts shall be remitted to you when you yourself shall have forgiven. Your sacrifices shall be received when you shall come in peace to God. Your thoughts and deeds shall be directed from above, when you consider those things which are divine and righteous, as it is written: “Let the heart of a man consider righteous things, that his steps may be directed by the Lord.”
Source: The Treatises of Cyprian (New Advent)