When old horses get warm, they are not easily held in.
More German Proverbs:
Never fight an enemy whilst it is possible to cheat him.German
Once a thief, always a thief.
German
He who dies for the truth finds holy ground everywhere for his grave.
German
Satiety causes disgust.
German
Ingratitude sickens benevolence.
German
Fools rush in where angels fear to tread.
German