Answer:
A [deadly] delightful sweet song that promises pleasure and knowledge.
The desire of Glory, just like the Iliad points out. The sirens also promise him the knowledge to victory.
Step-by-step explanation:
According to Homer, Odysseus goes in his journey and when they pass near the sirens they hear a sweet honey song, which offer delight and knowledge.
For a moment, Odysseus (Ulysses) feel tempted to fall into the delights of the knowledge the sirens have to offer, But He's tied to the mast of the ship and the crew.