5 So he took the troops down to the water. Then Hashem said to Gidon, “Set apart all those who lap up the water with their tongues like dogs from all those who get down on their knees to drink.”
va-YO-red et ha-AM el ha-MA-yim va-YO-mer a-do-NAI el gid-ON KOL a-sher ya-LOK bil-sho-NO min ha-MA-yim ka-a-SHER ya-LOK ha-KE-lev ta-TZEEG o-TO l’-VAD v’-KHOL a-sher yikh-RA al bir-KAV lish-TOT
ה וַיּוֹרֶד אֶת־הָעָם אֶל־הַמָּיִם וַיֹּאמֶר יְהֹוָה אֶל־גִּדְעוֹן כֹּל אֲשֶׁר־יָלֹק בִּלְשׁוֹנוֹ מִן־הַמַּיִם כַּאֲשֶׁר יָלֹק הַכֶּלֶב תַּצִּיג אוֹתוֹ לְבָד וְכֹל אֲשֶׁר־יִכְרַע עַל־בִּרְכָּיו לִשְׁתּוֹת׃
7:5 Set apart all those who lap up the water with their tongues
For it to be clear to all that the victory of the Israelites would be a miraculous one, Hashem orders Gidon to reduce the size of his army. He tells Gidon to send home all those who kneel down to drink water prior to the battle against Midian. Rashi says that the fact that they kneeled is proof that they had earlier knelt in worship of idols. Eretz Yisrael cannot tolerate idolatry (see Deuteronomy 29:24-27). Therefore, those soldiers who have previously engaged in such worship are the ones to be removed from this battle for control of the land.