Saint Gregory Nazianzen

Let it be assured that to do no wrong is really superhuman and belongs to God alone.

-- Saint Gregory Nazianzen

Saint Augustine of Hippo

God had one son on earth without sin, but never one without suffering. 

-- Saint Augustine of Hippo

Saint John Climacus

Our good Redeemer, by speedily granting what is asked, draws to His love those who are grateful. But He keeps ungrateful souls praying a long time before Him, hungering and thirsting for what they want, since a badly trained dog rushes off as soon as it is given bread and leaves the giver behind.

-- Saint John Climacus