When Moses was in the mountains spending time with God, Aaron, who witnessed God defeating Pharoah, formed an idol. Exodus 32:1 says, “When the people saw that Moses was so long in coming down from the mountain, they gathered around Aaron and said, ‘Come, make us gods who will go before us. As for this fellow Moses who brought us out of Egypt, we don’t know what has happened to him.” This idol was made with gold, and the people bowed down and worshiped it. When Moses traveled back down from the mountain, he was enraged. He asked God for forgiveness on their behalf. The people were ultimately struck with the plague.