Hecate wants them to lead Macbeth to destruction because she believes that men like Macbeth do nothing to help witches. Therefore, she sets up three misleading prophecies for the other witches to deliver, which will give Macbeth false hope.
Explanation:
The three witches continually deceive Macbeth by telling him enigmatic prophecies, which they know will propel him to act upon his ambitious motivation to become king. Macbeth and his wife then deceive the king and his court by acting as gracious hosts, while they plot in secret about killing him.
