The end of the first mishna of the second chapter of Pirkei Avos states “Consider three things and you will not come into the grip of sin: Know what is above you – a watchful Eye, an attentive Ear, and all your deeds are recorded in a Book.”

People tend to underestimate the significance of their actions and thoughts.  The Midrash (Vayikra Rabbah 34:9) teaches: Had Reuben known that God would write [in the Torah, that he had wanted to rescue Joseph], Reuben would have carried Joseph on his shoulders.  Had Boaz known that God would record that he had given some food to Ruth, he would have given her a sumptuous meal.

The mishna therefore teaches that all of our deeds are recorded in a Book because they truly are important.  If we are constantly aware of the significance of our actions and that everything is being recorded, it will prevent us from stumbling into sin.