10 “These same men shall mark my heel.” For they shall sojourn and hide in such sort, that they may mark where a man slips. Intent they are upon the heel, to see when a slip may chance to be made; in order that they may detain the foot for a fall, or trip up the foot for a stumble; certes that they may find that which they may accuse. And what man so walks, that nowhere he slips? For example, how speedily is a slip made even in tongue? For it is written, “Whosoever in tongue stumbles not, the same is a perfect man.” What man I pray would dare himself to call or deem perfect?
Therefore it must needs be that every one slip in tongue. But let them that shall sojourn and shall hide, carp at all words, seeking somewhere to make snares and knotty false accusations, wherein they are themselves entangled before those whom they strive to entangle: in order that they may themselves be taken and perish before that they catch other men in order to destroy them....Whatever good thing I have said, whatever true thing I have said, of God I have said it, and from God have said it: whatever other thing perchance I have said, which to have said I ought not, as a man I have said, but under God I have said.
He that strengthens one walking, does menace one straying, forgive one acknowledging, recalls the tongue, recalls him that slipped....Attend thou unto the discourses of him whom you blame, whether perchance he may teach you something to your health. And what, he says, shall he be able to teach to my health, that has so slipped in word? This very thing perchance he is teaching you to your health, that you be not a carper at words, but a gatherer of precepts. “As my soul has undergone.”
I speak of that which I have undergone. He was speaking as one experienced: “As my soul has undergone. They shall sojourn and hide.” Let my soul undergo all men, men without barking, men within hiding, let it undergo. From without coming, like a river comes temptation: on the Rock let it find you, let it strike against, not throw you down; the house has been founded upon a Rock. Within he is, he shall sojourn and hide: suppose chaff is near you, let there come in the treading of oxen, let there come in the roller of temptations; you are cleansed, the other is crushed.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)