Mother-in-law and daughter-in-law can be cooked together but they will never be tender.
More French Proverbs:
A restive morsel needs a spur of wine.French
When the words are said, the holy water is made.
French
A miserly father makes a prodigal man.
French
He who pays is fairly entitled to speak his mind.
French
When the Frenchman sleeps the devil rocks him.
French
Shoemakers are always the worst shod.
French