Why God Cherishes Israel Above the Nations at Ki Tisa

[(Exodus 30:12): "When you take up the head [i.e., take a census]."] What is written above in the matter? "And Aaron shall make atonement upon its horns" (Exodus 30:10). When Israel sinned, the Holy One, blessed be He, said to Moses: "Go, make atonement for them." He said before Him: "Master of the Universe, did You not say thus, 'once in the year'?" The Holy One, blessed be He, said to him: "Go, raise it up now." Rabbi Avin the Levite said: Moses said before the Holy One, blessed be He: "Master of the Universe, out of all the nations that You have in Your world, You charge me concerning none but Israel. 'And to the children of Israel you shall say' (Leviticus 20:2); 'To the children of Israel you shall speak' (Exodus 30:31)." To what is the matter comparable? To a king who had purple robes, and he had one purple robe that he cherished more than all of them. And he would command his servant, saying to him: "Shake it out, fold it," and he said to him: "Set your attention upon it." He said to him: "My lord the king, out of all your purple robes you charge me concerning none but this one." He said to him: "Because I wore that one when I first became king; therefore I cherish it more than all those purple robes of mine." So too the Holy One, blessed be He, when [Moses] said to Him: "Why do You charge me concerning Israel out of all the nations of the world?" He said to him: "Because they made Me king first, at the sea, and said, 'The Lord shall reign forever and ever' (Exodus 15:18)."