Answer: Circe warned Odysseus that the Sirens' songs would be irresistible to him and that he should take precautions to avoid succumbing to them.
When Odysseus decides to leave Circe's island, she gives him a piece of advice. She tells him that in his travels, he will pass the island of the Sirens. The Sirens have an irresistible voice, and their songs attract sailors to their death. She also tells him that, in order to protect himself and his crew, they should all put beeswax in their ears to avoid listening to the songs.