The scene of Macbeth meeting Three Witches for the first time is immensely inspired by the scene of Saul summoning Samuel in the battle's eve in the Bible.
Contemporary audiences and readers may find these two scenes less alike because the witchess seem very alive and vile creatures while Samuel the prophet and priest of the God was summoned from death as a soul.
However, we must bear in mind that in the Early Modern performance practices Three Witches were supposed to appear from the trap door on the floor. They were legitimately souls/demons from Hell. Samuel, though a saintly figure in his life, could only mean foul and evil when summoned as a soul, because the prominent traditional Hebrew idea of life afterdeath is to linger endlessly as pale souls in the Hell and not to be summoned by any means. Saul's employment of necromancy surely would evoke anger from God.
Therefore, Three Witches lead Macbeth into his doom, and Samuel prophesied that Saul should die tomorrow if only to deprive Saul of any hope that left.
(the idea that these two scenes are comparable is indebted to Robert Alter)
