2 Samuel 10:9-11

9Joab saw that there were two groups of the enemy's soldiers. They were ready to attack his army from different sides. So he chose some of Israel's best soldiers. Joab himself led them to attack the Syrian soldiers in the fields.

10He told his brother Abishai to lead the rest of Israel's army to fight against the Ammonites.

11Joab said to Abishai, ‘If the Syrian soldiers are too strong for me, you must come to rescue me. But if the Ammonites are too strong for you, I will come to rescue you.