1 Chronicles 19:8-13

8And when David heard of it, he sent Joab, and all the host of the mighty men. 9And the children of Ammon came out, and put the battle in array at the gate of the city: and the kings that were come were by themselves in the field.

10Now when Joab saw that the battle was set against him before and behind, he chose of all the choice men of Israel, and put them in array against the Syrians. 11And the rest of the people he committed into the hand of Abishai his brother; and they put themselves in array against the children of Ammon. 12And he said, If the Syrians be too strong for me, then thou shalt help me; but if the children of Ammon be too strong for thee, then I will help thee. 13Be of good courage, and let us play the man for our people, and for the cities of our God: and Jehovah do that which seemeth him good.