Chazal say (Avodah Zara 2B) that Hashem went to every nation (and asked if they wanted the Torah), and they did not accept it – until He came to Yisroel and they accepted it. Sefer Emes L’Yaakov quotes the Chozeh of Lublin zy”a as asking why Hashem did this. Didn’t He know that the nations wouldn’t want the Torah?
He answers that Shavuos is a time when we receive good influences for the entire year, just like on Rosh Hashanah. However, the Heavenly prosecutors try to obstruct us from receiving these hashpa’os. To silence them, Hashem clearly showed that the nations refused to accept the Torah, yet they still are provided for in this world. Accordingly, it is a kal v’chomer that the Jewish people, who willingly accepted the Torah, should receive these influences of goodness and blessing.
