Mishnah — Seder Nezikin, Tractate MakkotChapter 3…
“ How much untithed produce must one eat to be liable [for lashes] ? Rabbi Shimon says "any amount", and the Rabbis say the volume of an olive. Rabbi Shimon said to them, "Don't you agree with me that if someone eats a tiny ant that he is liable [for lashes] ?" ”
