Free Will and the Covenant at Sinai

Rav Saadia taught that Hashem created man with free will, the ability to choose his own conduct, and he placed great weight on the covenant at Sinai, in which Bnei Yisroel freely obligated themselves to Hashem. Without free will, he explained, there would be no difference between a mitzvah and a sin, punishment would make no sense, and mitzvos would have no meaning, since a commandment requires someone capable of accepting it.