All these however were good shepherds, not because they shed their blood, but because they did it for the sheep. For they shed it not in pride, but in love. Should any among the heretics suffer trouble in consequence of their errors and iniquities, they forthwith boast of their martyrdom; that they may be the better able to steal under so fair a cloak: for they are in reality wolves. But not all who give their bodies to be burned, are to be thought to shed their blood for the sheep; rather against the sheep; for the Apostle saith, Though I give my body to be burned, and have not charity, it profiteth me nothing. (1 Cor. 13:3) And how hath he even the smallest charity, who does not love connexion (convictus) with Christians? to command which, our Lord did not mention many shepherds, but one, I am the good Shepherd.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: de Verb. Dom. Serm. 1