There is besides a story, that Hannibal, when about nine years old, while he boyishly coaxed his father Hamilcar that he might be taken to Spain, (at the time when the African war was completed, and he was employed in sacrificing previously to transporting his army thither,) was conducted to the altar; and, having laid his hand on the offerings, was bound by an oath to prove himself, as soon as he could, an enemy to the Roman people.
Hor Book XXI Chapter 1: Introduction and youth of Hannibal

It was obvious that he was revolving in his mind a greater war than he was then engaged in; and that if he had lived longer, the Carthaginians under Hamilcar would have carried the war into Italy
Hor Book XXI Chapter 2: Hasdrubal