Still waters run deep. 
A good man is hard to find Link to proverb. 
Nothing succeeds like success Link to proverb. 
He who sups with the devil should have a long spoon Link to proverb. 
A golden key can open any door Link to proverb. 
There but for the grace of God, go I Link to proverb. 
You can't make a silk purse out of a sow's ear.