Rashi on Numbers 14:4/רש"י על במדבר י״ד:ד׳

1נתנה ראש LET US MAKE A CAPTAIN — Understand this as the Targum does: Let us appoint a chief — i.e. let us set a king over us. But our Rabbis explain the word ראש to denote idol-worship (i.e. that they intended to turn to idolatry) (cf. Sanhedrin 107a).