From his Homily VIII on Philippians:
Taking these things to heart, let us do everything “without murmuring and disputing.” Is it some good work that thou hast before thee, and dost thou murmur? wherefore? art thou then forced? for that there are many about you who force you to murmur, I know well, says he. This he intimated by saying, “in the midst of a crooked and perverse generation”; but it is this that deserves admiration, that we admit no such feeling when under galling provocation. For the stars too give light in the night, they shine in the dark, and receive no blemish to their own beauty, yea they even shine the brighter; but when light returns, they no longer shine so. Thus thou too dost appear with the greater lustre, whilst thou holdest straight in the midst of the crooked. This it is which deserves our admiration, the being “blameless”; for that they might not urge this plea, he himself set it down by anticipation.