Numbers 15:27

תחטא בשגגה [AND IF ANY SOUL (i.e. any individual)] SIN THROUGH ERROR, by committing idolatry, עז בת שנתה [HE SHALL BRING] A SHE GOAT OF ONE YEAR [FOR A SIN OFFERING] — For other sins committed in error an individual may bring either a she-lamb or a she-goat as a sin-offering, whilst in the case of this (the sin of idolatry) Scripture has appointed a she-goat for it (Sifrei Bamidbar 112:1).

וְאִם־נֶ֥פֶשׁ אַחַ֖ת תֶּחֱטָ֣א בִשְׁגָגָ֑ה וְהִקְרִ֛יבָה עֵ֥ז בַּת־שְׁנָתָ֖הּ לְחַטָּֽאת׃

And if a single person sin through ignorance, then he shall bring a she goat of the first year for a sin offering.