Parshanut su Deuteronomio 26:18

To be for Him a treasured people: In Torah and mitzvos. "And to place you above... for praise and for renown and for glory." This means with wisdom, with wealth, with nice customs and order. To be a holy people means to not become mixed with the gentile nations and not to act as they do. You shall be separated and distinguished from them through purity and holiness. For when the Jewish people are downtrodden amongst the gentile nations, in our great sins, they try to find favor in the eyes of the nations of the world, "and act as the most depraved amongst them," and there are some that intermarry with them. However this is not the case when they are held up "for praise and renown," "and above all the nations" - they will [then] be a holy people separated and distinguished.