"And he led out his trained men" (Genesis 14:14) — he emptied them out like a weapon, as you say, "I will draw my sword" (Exodus 15:9). And why were they called "his trained men"? Because of the commandment concerning warfare. And once he recited to them the passage of the officers, they were afraid and said: How shall we make war against four kings who defeated five and went on their way? And there remained with him, of those born in his house who were with him, none but Eliezer alone; and thus does the reckoning of the letters of his name come out [to three hundred and eighteen]. "And he pursued as far as Dan" (Genesis 14:14) — once he reached Dan his strength grew weak, on account of the calves of Jeroboam, as it is written, "And he set the one in Beth-el, and the other he placed in Dan" (1 Kings 12:29).
Abraham Arms His Trained Men and His Strength Fails at Dan
Midrash Aggadah, Genesis 14:14
וירק את חניכיו. הריקן ככלי זיין, כמה דאת אמר אריק חרבי (שמות טו ט), ולמה נקרא שמם חניכיו במצות מלחמה, וכיון שאמר להם פרשת שוטרים נתייראו ואמר היאך נעשה מלחמה עם ד' מלכים שנצחו ה' והלכו להם, ולא נשתייר עמו מאותם ילידי ביתו שהיו עמו, אלא אליעזר בלבד, וכן הוא עולה חשבון אותיותיו: וירדוף עד דן. כיון שהגיע עד דן תשש כחו מפני עגלי ירבעם, דכתיב וישם את האחד בבית אל והאחד נתן בדן (מ"א יב כט):