Send for yourself men to scout the land of Canaan, which I am giving to the children of Israel; one man each for his father’s tribe you shall send, every one a prince among them.
Chabad.org — English translation + Rashi
Torah Temimah on Numbers 13:2 (איש אחד איש אחד): Yerushalmi Sotah 7:5 — dispute of R’ Akiva and R’ Yishmael on doubled language (12 vs 24 scouts).
Sefaria — Yerushalmi Sotah 7:5
English: According to R’ Akiva, who says doubled expressions are expansions — there were twenty-four; according to R’ Yishmael, who says they are ordinary doubled speech — there were twelve.
Ribui vs ordinary speech — whether doubled “ish ish” multiplies the count of scouts.
The Tannaim dispute whether the verse implies twelve or twenty-four men sent to scout the land.