I am sure the grapes are sour.
He that has many friends, has no friends.
A liar will not be believed, even when he speaks the truth.
The cat always leaves a mark on his friend.
An oak and a reed were arguing about their strength. When a strong wind came up, the reed avoided being uprooted by bending and leaning with the gusts of wind. But the oak stood firm and was torn up by the roots.
Appearances are often deceiving.