Moses had promised the children of Israel that he would return after forty days. The fortieth day had arrived and the people became anxious and nervous. During Moses' long absence, the Egyptian riff-raff that had accompanied the children of Israel since their exodus from Egypt spread the word around that Moses would never return and that they had better choose another leader to be the intermediary between them and G‑d. The children of Israel did not realize that Moses had meant that he would return after the completion of forty full days. Therefore, when the sixteenth of Tammuz, which was the fortieth day since the Revelation, arrived, and Moses had not returned, they stormed against Aaron and Hur, Miriam's son, who had temporarily taken over the leadership of the Jewish camp, demanding that they make an idol to take Moses' place.
In vain did Hur try to talk the excited group of ringleaders out of their plan. His persistent refusal to go ahead with it enraged them so much that they killed him. Now Aaron saw that there was little chance of stopping them. He would only share a similar fate, and the people would have committed the indelible crime of having murdered their own High Priest.
Aaron Plays for Time
Aaron knew that Moses would return the next morning. He therefore decided to play for time. He asked everyone to bring his own and his wife's gold and jewelry for the purpose of making the idol. Thus, he thought, he would delay the whole affair, since he expected that the people would refuse to part with their precious jewelry and ornaments. But contrary to his expectations, the mob willingly parted with their gold, though the women did refuse to be a party to it. Aaron had no other choice but to take the heap of golden rings, chains, and bracelets that had been piled up before him and throw it into the melting-pot. Applying their knowledge of magic, the Egyptian conspirators made the gold assume the form of a calf.
When the children of Israel saw it, they believed that it was to be their representative before G‑d, and they wanted to pay homage to it. But Aaron made another desperate effort to delay the idolatry. He told the people that on the next day he would build an altar, and proclaim a special day of worship.
Meanwhile, G‑d informed Moses of the downfall of the children of Israel, and of the severe punishment that awaited them. They would die, and a new people, descendants of Moses, would take their places, to carry the torch of the Divine Law among the nations of the world.
Moses was greatly distressed. In moving words, he prayed and implored G‑d to spare the Jewish people. Moses recalled G‑d's covenant with Abraham, Isaac, and Jacob, and for their sake begged G‑d's forgiveness. Finally, G‑d's mercy was aroused, and He promised to spare the people of Israel.
Assured of G‑d's forgiveness, Moses descended from Mount Sinai. Exactly forty days had passed since he had gone up, and in his hands he carried the Tables of Testimony, written by G‑d Himself. At the foot of the mountain his disciple Joshua awaited him, and together they approached the camp of Israel.
When they came within hearing distance of the camp, shouts of jubilation and joy reached their ears. Moses soon saw what was going on. In despair, he threw the Tables of Testimony to the ground, shattering them into small pieces. A people who could worship a golden calf so soon after they faced G‑d and heard His voice say, "Thou shalt not make thee a graven image," did not deserve this treasure, Moses thought. Then he took the golden idol, ground it to dust and spread the dust over the water, which he made the people drink. Thus he showed them the impotence of their idol, and the foolishness of their action.
Punishment of the Guilty
Taking up a position near the entrance of the camp, Moses said: "Whoever is with G‑d, come to me!" The entire tribe of Levi gathered about him, and Moses ordered them to slay every one guilty of worshipping the Golden Calf, regardless of his position and relationship to them. That day, the seventeenth day of Tammuz, three thousand men of the children of Israel lost their lives, in punishment for their idolatry.
The next day Moses again told the people that they had gravely sinned against G‑d, and that he would now go to pray for atonement. Moses went up to Mount Sinai, and prayed to G‑d for forty days and forty nights, while the people mourned their dead, and made atonement for their sin.
After Moses had descended from: Mount Sinai, G‑d told him to hew another pair of tables, similar to the one he had received the first time. Moses was then to ascend Mount Sinai for the third time, when G‑d would inscribe upon them the Ten Commandments, as He had done before.
On the first day of Elul, Moses went up to Mount Sinai and stayed with G‑d for the third time, for forty days and forty nights, neither eating nor sleeping. G‑d inscribed the Ten Commandments on the tables and told Moses He forgave the children of Israel.
G-D Forgives the People
Holding the newly made tablets in his hands, Moses stood on Mount Sinai and
G‑d taught him how the children of Israel could make atonement for their sins through real repentance and prayer. G‑d proclaimed the "thirteen attributes" which the children of Israel were to recite on their days of repentance (Exodus 34:6-7): "L-rd, L-rd, benevolent G‑d, slow to anger and abundant in loving kindness and truth, preserving loving kindness for thousands, forgiving iniquity and rebellion and sin; yet He does not completely clear [of sin] He visits the iniquity of parents on children and children's children, to the third and fourth generations."
Moses bowed down before G‑d and said: "If I have now found favor in Your eyes, O Lord, let the Lord go now in our midst [even] if they are a stiff necked people, and You shall forgive our iniquity and our sin and thus secure us as Your possession"
In reply, G‑d told Moses: "Behold, I will form a covenant; in the presence of all your people, I will make distinctions such as have not been created upon all the earth and among all the nations, and all the people in whose midst you are shall see the work of the Lord how awe inspiring it is that which I will perform with you."
It was the tenth day of the month of Tishrei -- Yom Kippur -- when Moses returned to the camp of Israel, with the new Tables of Testimony in his hands. Moses' face shone with a Divine light that frightened Aaron and the children of Israel. They drew back in awe when Moses approached them. On learning of this, Moses covered his face with a veil. Without delay, he proceeded to teach the children of Israel the entire contents of the Torah which G‑d had given him on Mount Sinai.