Mishnah 3 - Chapter 1 - Pirkei Avot

Antigenos ish socho kibbel mishim'on hatzaddik. Hu hayah omer. Al tihyu cha'avadim hamshammeshin et harav al menat lekabbel peras, ella hevu cha'avadim hamshammeshin et harav shello al menat lekabbel peras, vihi mora shamayim aleichem.

Antigonus a man of Socho received [the oral tradition] from Shimon the Righteous. He used to say: do not be like servants who serve the master in the expectation of receiving a reward, but be like servants who serve the master without the expectation of receiving a reward, and let the fear of Heaven be upon you.

Antignos Ish Socho received it from Shimon Hatzaddik: He was wont to say: Do not be like servants who serve their master in order to receive pras ["valuation," as in the targum of (Leviticus 5:15): "your valuation" — "bepursaneh," what one gives one who serves him, though he is not required by law to give him anything, as what one gives his young son or his wife or his servant because of the pleasure that he gives him. One should not serve his Creator even in the expectation of such pras], but be like servants who serve their master not in order to receive pras, [but out of love alone]. And let the fear of the L rd be upon you. [Even though you serve Him out of love, serve Him also out of fear. For one who serves out of love is zealous in the performance of positive commandments, while one who serves out of fear is heedful in the observance of negative commandments, so that his service is found to be complete. And thus did our sages say: "Serve out of love and serve out of fear. Serve out of love, so that if you are moved to hate, know that you love, and a lover does not hate. Serve out of fear, so that if you are moved to "kick," know that you fear, and a fearer does not kick."]