5 What follows? “Let them be turned away immediately blushing, that say to me, Well, well”. Two are the kinds of persecutors, revilers and flatterers. The tongue of the flatterer does more persecute than the hand of the slayer: for this also the Scripture has called a furnace. Truly when the Scripture was speaking of persecution, it said, “Like gold in a furnace it has proved them” (speaking of Martyrs being slain), “and as the holocaust's victim it has received them.” Hear how even the tongue of flatterers is of such sort: “The proving,” he says, “of silver and of gold is fire; but a man is proved by the tongue of men praising him.” That is fire, this also is fire: out of both you ought to go forth safe. The censurer has broken you, you have been broken in the furnace like an earthen vessel. The Word has moulded you, and there has come the trial of tribulation: that which has been formed, must needs be seasoned; if it has been well moulded, there has come the fire to strengthen. Whence He said in the Passion, “Dried up like a potsherd has been My virtue.” For Passion and the furnace of tribulation had made Him stronger....
Source: The Enarrations, or Expositions, on the Psalms (New Advent)