וַיִּרְדֹּ֣ף דָּוִ֔ד ה֖וּא וְאַרְבַּע־מֵא֣וֹת אִ֑ישׁ וַיַּֽעַמְדוּ֙ מָאתַ֣יִם אִ֔ישׁ אֲשֶׁ֣ר פִּגְּר֔וּ מֵעֲבֹ֖ר אֶת־נַ֥חַל הַבְּשֽׂוֹר׃
But David pursued, he and four hundred men; for two hundred stayed behind, who were so faint that they could not go over the brook Besor.
Read midrashic interpretation of I Samuel 30:10: and classical rabbinic exegesis.