These would be my personal favorite proverbs:
When shepherds quarrel, the wolf has a winning game. - German Proverb
Unlooked-for often comes. - German Proverb
He keeps his road well enough who gets rid of bad company. - Portuguese Proverb
Drink upon salad costs the doctor a ducat; drink upon eggs costs him two. - German Proverb
It's no delay to stop to edge the tool. - Irish Proverb