Final answer:
The Israelites break the Covenant by worshipping a golden calf idol while Moses is away receiving the Ten Commandments, leading to Moses breaking the stone tablets in anger.
Step-by-step explanation:
The Covenant is broken when Moses leaves for Mount Sinai for 40 days and the Israelites engage in the worship of a golden calf idol. This act of idolatry occurs during Moses' absence, when he is receiving the Ten Commandments, which include the commandment against making graven images. The people's actions lead Moses to break the stone tablets in anger when he comes down from the mountain and sees them worshiping the calf, as described in the Old Testament. Their actions represent a direct violation of the agreement to worship only Yahweh and to follow his commandments, thereby breaking the Covenant they had established with God.