וַתַּעֲרֹ֤ךְ יִשְׂרָאֵל֙ וּפְלִשְׁתִּ֔ים מַעֲרָכָ֖ה לִקְרַ֥את מַעֲרָכָֽה׃
And Israel and the Philistines put the battle in array, army against army.
Read halakhic rulings (Jewish law) on I Samuel 17:21 from the Mishneh Torah and classical halakhic sources, free online.