In several places throughout the Torah (Sh’mos 19:5 and D’varim 7:6, 14:2, 26:18), Hashem refers to the Jewish People as an am s’gulah. In this context, it means that they possess certain traits that supersede the rules of creation. For instance, according to Chazal, if a Jew intends to perform a mitzvah and is prevented from doing so, he receives reward as if he performed it. If, on the other hand, he is prevented from performing a transgression, this same principle will not apply. He is not held accountable (Kiddushin 40a).