What does 1 Samuel 24:4 mean?

David's men whispered to him, This is the day the Lord promised you: 'I'm handing your enemy over to you. Do whatever you want with him.' David got up quietly and cut off a corner of Saul's robe without being noticed. 1 Samuel 24:4 - Modern Text Bible

(David's men see this as a God-given chance to kill Saul, but David only sneaks up and cuts a piece of Saul's robe instead.)