כִּֽי־תֵצֵ֨א לַמִּלְחָמָ֜ה עַל־אֹיְבֶ֗יךָ וְֽרָאִ֜יתָ ס֤וּס וָרֶ֙כֶב֙ עַ֚ם רַ֣ב מִמְּךָ֔ לֹ֥א תִירָ֖א מֵהֶ֑ם כִּֽי־יְהוָ֤ה אֱלֹהֶ֙יךָ֙ עִמָּ֔ךְ הַמַּֽעַלְךָ֖ מֵאֶ֥רֶץ מִצְרָֽיִם׃
When thou goest forth to battle against thine enemies, and seest horses, and chariots, and a people more than thou, thou shalt not be afraid of them; for the LORD thy God is with thee, who brought thee up out of the land of Egypt.
Read halakhic rulings (Jewish law) on Deuteronomy 20:1: and classical halakhic sources.