2 Samuel 10:11 (BSB)

“If the Arameans are too strong for me,” said Joab, “then you will come to my rescue. And if the Ammonites are too strong for you, then I will come to your rescue.

From 2 Samuel 10. Also in the ESV.

Commentary on 2 Samuel 10:11

• Matthew Henry (Presbyterian), Matthew Henry's Complete Commentary on 2 Samuel 10:6-14: Here we have, I. The preparation which the Ammonites made for war, Sa2 10:6. They saw they had made themselves very odious to David and obnoxious to his just displeasure. This they might easily have foreseen when they abused his ambassadors, which was no other than a challenge to war, and a bold defiance of him.
• John Gill (Reformed Baptist), Exposition of the Old and New Testaments on 2 Samuel 10:11: And he said, if the Syrians be too strong for me,.... Which he might perceive by Joab's forces giving way, or by some signal agreed on between them then thou shall help me; detach a part of his army to his support and assistance: but if the children of Ammon be too strong for thee, then I will come and help thee; in the same manner.
• Keil & Delitzsch (Lutheran), Biblical Commentary on the Old Testament on 2 Samuel 10:9-11: 2Sa 10:9-11 When Joab saw that “the front of the war was (directed) against him both before and behind,” he selected a picked body out of the Israelitish army, and posted them (the picked men) against the children of Aram (i.e., the Syrians). The rest of the men he gave to his brother Abishai, and stationed them against the Ammonites.