Horav Nissan Alpert z.l., offers an anecdote in explanation of this pasuk: A Jew once stood before a gentile magistrate, attempting to describe to him the greatness of the saintly Chafetz Chaim z.l. He told how the Chafetz Chaim’s prayers penetrated the Heavens to implore the Almighty’s blessing for those in need. He described the Chafetz Chaim’s spiritual eminence and his ability to have miracles made for him. The judge brushed him aside, refusing to believe all of the stories. Hearing the disdain in the gentile’s voice, the Jew looked into his eyes and, in an accusing voice said, “My lord, if the stories about the great Chafetz Chaim are not true, then why do they not relate such stories about you? We must, therefore, assume that the stories are true.”
This is what the Torah is saying to us. If we need some “proof” of the validity of the Revelation and the Giving of the Torah, we have to take into consideration that we are the only nation about whom history records the Revelation at Sinai. The fact that this magnificent occurrence is not attributed to any other nation, in itself provides indisputable proof of our selection as the chosen people.