Hebrews 10:24-25
What then if he be evil (you say)? So much the greater is the reward. Even for his wickedness you ought to feel grateful to him: even should he be evil after receiving ten thousand kindnesses. For if he were not exceedingly evil, your reward would not have been exceedingly increased; so that the reason you assign, for not loving him, the saying that he is evil, is the very reason for loving him. Take away the contestant and you take away the opportunity for the crowns. Do you see not the athletes, how they exercise when they have filled the bags with sand?
But there is no need for you to practice this. Life is full of things that exercise you, and make you strong. Do you see not the trees too, the more they are shaken by the winds, so much the more do they become stronger and firmer? We then. if we be long-suffering, shall also become strong. For it is said, “a man who is long-suffering abounds in wisdom, but he that is of a little soul is strongly foolish.” Do you see how great is his commendation of the one, do you see how great his censure of the other?
“Strongly foolish,” i.e. very [foolish]. Let us not then be faint-hearted one towards another: for this does not rise from enmity, but from having a small soul. As if the soul be strong, it will endure all things easily, and nothing will be able to sink it, but will lead it into tranquil havens. To which may we all attain, by the grace and lovingkindness of our Lord Jesus Christ, with whom to the Father together with the Holy Ghost, be glory, power, honor, now and for ever and world without end. Amen.
Source: Homilies on the Epistle to the Hebrews (New Advent)