The Scripture says that it is Samuel talking. However, the context seems to forbid us to disturb those who are at rest. Samuel seems angered as to why he was disturbed. Now Saul requested Samuel to ask a favor from God. But Saul refused to do so and reiterated the prophecy about his downful at the hands of the Philistine. We may conclude that Saul's consultation with this woman adds to his sins and violations of God's will. I hope this helps.