"Gather to Me" (Numbers 11:16). [This is what Scripture says (Proverbs 22:11): "One who loves purity of heart, grace upon his lips — a king is his friend."] Why did He not say to him "seventy men" (anashim, in the plural), but rather "seventy man" (ish, in the singular)? Rather, [He said to him: seventy distinguished individuals (ish)] who resemble Me and you — (Exodus 15:3) "The LORD is a man (ish) of war," and (Numbers 12:3) "Now the man (ish) Moses."
Why God Said Seventy Ish When Gathering the Elders
Midrash Tanchuma Buber, Beha'alotcha 26:1
אספה לי. [זש"ה אוהב טהר לב חן שפתיו רעהו מלך] (משלי כב יא), למה לא אמר לו שבעים אנשים, אלא שבעים איש, אלא [א"ל שבעים איש מיוחדים] שהם דומין לי ולך, ה' איש מלחמה (שמות טו ג), והאיש משה (במדבר יב ג).