Rabbi Joshua son of Korchah taught that Moses stayed on Mount Sinai 40 days and 40 nights, reading the Written Law by day, and studying the Oral Law by night. After those 40 days, on the 17th of Tammuz, Moses took the Tablets of the Law, descended into the camp, broke the Tablets in pieces, and killed the Israelite sinners. Moses then spent 40 days in the camp, until he had burned the Golden Calf, ground it into powder like the dust of the earth, destroyed the idol worship from among the Israelites, and put every tribe in its place. And on the New Moon (, "Rosh Chodesh") of Elul (the month before Rosh Hashanah), God told Moses in "Come up to Me on the mount," and let them sound the shofar throughout the camp, for, behold, Moses has ascended the mount, so that they do not go astray again after the worship of idols. God was exalted with that shofar, as says, "God is exalted with a shout, the Lord with the sound of a trumpet." Therefore, the Sages instituted that the shofar should be sounded on the New Moon of Elul every year.