What does 2 Samuel 20:6 mean?

David said to Abishai, 'Sheba, son of Bichri, will do us more harm than Absalom did. Take my men and chase him down before he finds a fortified city and escapes.' 2 Samuel 20:6 - Modern Text Bible

(David, worried about the threat Sheba poses, tells Abishai to act fast before Sheba can hide and start a bigger rebellion.)