וַתְּהִ֞י הַמַּכָּ֣ה הָרִאשֹׁנָ֗ה אֲשֶׁ֨ר הִכָּ֧ה יוֹנָתָ֛ן וְנֹשֵׂ֥א כֵלָ֖יו כְּעֶשְׂרִ֣ים אִ֑ישׁ כְּבַחֲצִ֥י מַעֲנָ֖ה צֶ֥מֶד שָׂדֶֽה׃
And that first slaughter, which Jonathan and his armour-bearer made, was about twenty men, within as it were half a furrow’s length in an acre of land.
Read midrashic interpretation of I Samuel 14:14: and classical rabbinic exegesis.