Parashas Vayikra · Aliyah 5 · Passuk 2
Chabad.org — English translation + Rashi
Torah Temima points to Keritot / Horayot / Toras Kohanim on the scope of chatat.
E-Daf / Tsurras Hadaf
PDF of the daf / source
English: If a person sins unwittingly regarding any of Hashem’s commandments that may not be done.
Definition of the chatat obligation — shogeg on a lav that carries kares when done bemezid.
Chatat is brought for an unwitting violation of a negative commandment (one of the mitzvot that “shall not be done”), not for every mistake. The classic case is a kares-prohibition transgressed be-shogeg.