אשמנו
“We have transgressed.”

QUESTION: Why does one strike his chest over his heart with his hand when reciting the confession?

ANSWER: According to Torah law, one cannot be found guilty lest there are witnesses who testify to the crime. In the prayer of “Unetanah tokef kedushat hayom” — “Let us proclaim the mighty holiness of this day” — we proclaim, “You open the Book of Remembrance and it reads itself; every man’s signature is in it.” Thus, by applying his signature to all his deeds, the person serves as the witness who attests to the validity of his actions.

The Torah prescribes that when punishment is meted out, “The hand of the witnesses shall be upon him first to put him to death” (Devarim 17:7). Thus, in keeping with this rule, the hand — which is the witness — is, so to speak, the first to apply punishment. It strikes the heart because it is the power in the body that, through expressing its desires, causes man to sin.

(אגרת הטיול, ועי' מדרש רבה קהלת ז:ה)

Perhaps, the striking of the chest over the heart is because it is the person’s life source and through sin one affects his very life.

(עי' אגרת התשובה פ"ה)

The Chofetz Chaim once said, “It is not the one who knocks on his heart for his sins that Hashem forgives; rather it is the one whose heart pounds him for the sins he committed.”