Avodah appears more than 140 times in the Hebrew Bible. Every appearance sharpens the same idea: the work God gives His people is inseparable from the worship He receives from them.
Genesis: Avodah as vocation
Adam is given avodah before he is given commandments. Work precedes law.
Exodus: Avodah as liberation
Pharaoh demanded avodah. So does God. The difference is not the labor — it is the master. Israel is freed from slavery into service.
The Prophets: Avodah as justice
Isaiah rebukes worship without righteousness. The avodah God wants includes how you pay your workers and welcome the stranger.