כל שיראת חטאו קודמת לחכמתו (אבות ג:ט)

Why does the Mishnah say “יראת חטאו”—his fear of sin—instead of simply “יראת חטא”?

The Tanna is teaching a profound lesson. Every person is judged according to their own level and understanding; therefore, each person has their own measure of yiras cheit. Even a young child, who has not yet attained a mature level of yiras Shamayim, must be taught, according to his capacity, to fear doing what is wrong.

True Torah can endure only when it is built upon a foundation of yiras cheit that is appropriate for the individual. This is why the Mishnah says “יראת חטאו”—his personal fear of sin—because each person must develop that foundation according to his unique situation and spiritual level.