2 Samuel 2:28

So Joab blew a trumpet, and all the people stood still, and pursued after Israel no more, neither fought they any more.

Cross-reference

In 2 Samuel 18:16, Joab again halts pursuit by blowing a trumpet, mirroring his earlier tactic to stop the battle with Abner.

In 2 Samuel 20:22, Joab again uses the trumpet to signal an end to pursuit, repeating the same military signal from the Abner campaign.

In 1 Samuel 13:3, Saul blows a trumpet to start war — here Joab blows to stop fighting, opposite purposes.