(Ibid. 5:4) "And the children of Israel did so, and they sent them outside the camp": R. Yossi Haglili says: Come and see how great is the power of transgression. For before they stretched forth their hands to transgress (with the golden calf), there were no zavim or lepers among them, and after they did so, there were zavim and lepers among them. In the course (of our learning) we learned that these three things (zavim, lepers, and tamei meth) occurred on the same day (the day that they made the golden calf).
R. Shimon b. Yochai says: Come and see how great is the power of transgression. For before they stretched forth their hands to transgress, what is written of them? (Shemot 24:17) "and the sight of the glory of the L-rd was like a consuming fire on the top of the mountain in the eyes of the children of Israel" — They did not fear and they did not tremble. After they stretched forth their hands to transgress, what is written of them? (Ibid. 34:30) "And Aaron and all of Israel saw Moses, and, behold, the skin of his face shone, and they were afraid to approach him."
"And the children of Israel did so": This is to declare the praise of Israel, that just as Moses told them, thus did they do. What is the intent of (the additional) "As the L-rd spoke to Moses, so did the children of Israel do"? To teach that the unclean ones themselves, (who were sent out), did not protest.