más sabe el diablo por viejo que por diablo 41
It is one of the variants that has this saying in Spain, and alludes to the value of experience, the wisdom given by the years, even higher than that which a devil can have with its angelic origin. In this case the phrase seems drawn from the novel "Tiger John : The healer of his honor." ( Ramón Pérez de Ayala, 1926). In Argentina is used more "the devil knows by devil but more knows by old".