2 Samuel 15:7-10

15:7 After four years Absalom said to the king, “Let me go and repay my vow that I made to the Lord while I was in Hebron. 15:8 For I made this vow when I was living in Geshur in Aram: ‘If the Lord really does allow me to return to Jerusalem, I will serve the Lord.’” 15:9 The king replied to him, “Go in peace.” So Absalom got up and went to Hebron.

15:10 Then Absalom sent spies through all the tribes of Israel who said, “When you hear the sound of the horn, you may assume that Absalom rules in Hebron.”