Bible History Online - Apis the Sacred Bull of Egypt

The bull symbolized fearless vigor, strength, and enduring fury. Egypt chose this animal to represent God and bull worship became prevalent in the ancient world. After the Israelites were delivered from Egypt, Moses came down from the mountain and found Aaron had set up a golden calf or young bull, that the people might worship God in this form. When the northern kingdom of Israel divided from their brothers in the south, Jeroboam introduced bull worship and set up two idols, one at Bethel and the other at Dan.

"And all the people brake off the golden earrings which were in their ears, and brought them unto Aaron. And he received them at their hand, and fashioned it with a graving tool, after he had made it a molten calf: and they said, These be thy gods, O Israel, which brought thee up out of the land of Egypt."

- Exodus 32:3,4

"God brought them out of Egypt; he hath as it were the strength of a bull."

- Numbers 23:22

"Whereupon the king took counsel, and made two calves of gold, and said unto them, It is too much for you to go up to Jerusalem: behold thy gods, O Israel, which brought thee up out of the land of Egypt. And he set the one in Bethel, and the other put he in Dan."

- 1 Kings 12:28-29