When Joab came out from David, he sent messengers after Abner, and they brought him back from the cistern at Sirah, but David did not know it. Bible

“the well of Sirah.” According to ancient witnesses and modern historians and archaeologists, this is almost certainly a place about 2.5 miles northeast of Hebron. This means that when Joab came back from raiding and met David, Abner had just left, which is supported by 2 Samuel 3:22, which indicates that that is what happened. The fact that Abner did not get very far was likely one reason Abner agreed to go back to Hebron.

Commentary for: 2 Samuel 3:26