Who proves too much proves nothing.
More French Proverbs:
Loaves put awry into the oven come out crooked.French
There are more buyers than connoisseurs.
French
Do you want better bread than wheaten?
French
The first half of life is spent in longing for the second, the second half in regretting the first.
French
Who rises late must trot all day.
French
After the daughter is married, then come sons-in-law in plenty.
French