Zwingli on Those Who Will Only Do, If In Doing They Receive a Reward

Those who so persistently demand a reward for their works, and say that they will cease working the works of God if no reward awaits the works, have the souls of slaves. For slaves work for reward only, and lazy persons likewise. But they that have faith are untiring in the work of God, like the son of the house. — Huldrych Zwingli