Though he spare it, and forsake it not; but keep it still within his mouth:
Read Chapter 20
Gregory The Dialogist
AD 604
14. For the evil that he delights in he ‘spares,’ because he does not, by practising penance, hunt it down in himself. Whence too it is added; and forsake it not. For if he had the mind to ‘forsake,’ he would not ‘spare’ it, but would pursue it closely. Now he ‘keeps it within his throat;’ because he so retains it in thought, that he never utters it in speech.