Kabbalah zu Dewarim 14:2

Rabbi Yehuda said, Heaven forbid that Bilaam would have any knowledge of the upper holiness. This is because the Holy One, blessed be He, desires no other people or tongue to make use of His glory, but His holy children alone, that is, Yisrael, who are called 'children to Hashem'. He said, "you shall therefore sanctify yourselves, and you shall be holy" (Vayikra 11:44), which means that those who are holy shall use holy things. And only Yisrael are holy, as it is written, "For you are a holy people" (Devarim 14:2); you, and no other people, are holy.