Rebbi says: Which is the proper path that a person should choose for himself? Whatever [path] is a benefit to himself and earns him the praise of fellow men. Be as scrupulous in performing a “minor” mitzvah as in a “major” one, for you do not know the reward given for the [respective] mitzvos. Calculate the cost of a mitzvah against its reward, and the reward of a sin against its cost. 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.