Read Commentary-Chapter 1, Mishnah 3

Antignos of Socho received the tradition from Shimon the Righteous. He would say: Do not be as slaves, who serve their master for the sake of reward. Rather, be as slaves who serve their master not for the sake of reward. And the fear of Heaven should be upon you.

Although we know that everything we do for Hashem should be not for the sake of reward (i.e. "heaven", unlike popular theology teaches us), but for the sake of our love for Hashem alone—many doctrines are formed around the antithesis of this statement. Preachers are peddling either "tickets to eternity" or "fire insurance". They leave out the part about a covenantal relationship with the Creator & King of the Universe. Their doctrine only is concerned about one thing: where a person will spend eternity—in the blissful euphoria of a heavenly realm, or the burning pits of hell. I'm afraid neither of these is what salvation is all about. Salvation, in its purist sense, is about having Hashem as your ally in the battles of life, your friend in times of trouble. It's about not having Him as your enemy, because there is no defense against His wrath. It's about living in covenantal relationship with the Almighty, and having no regrets when He says "Well done, my good and faithful servant." Salvation is now. Salvation is a process (of self-transformation). Salvation is not necessarily a destination.

I don't have time to elaborate on this much, but this is also a classic example of how something can be said, misunderstood, and entirely new doctrines formed around the misunderstanding. It is taught that after Antignos made this statement, his disciples after him began to teach that since we do not serve Hashem for reward, there must not be a reward, and thus began to teach that there was no resurrection. This is traditionally how the heretical sects of the Sadducees and Beothusians got started. This is why it is so important that those of us who are teachers are teaching as much truth as possible, and making sure we are understood properly. We will touch on this more in Mishnah 11.