The answer is: Other gods

Exodus 20:3 - The first commandment explicitly prohibits the worship of other gods, highlighting Israel's unique covenant with the Lord. This theme is echoed throughout the Bible, especially in Deuteronomy (6:14) and Joshua (24:15), reinforcing God's demand for loyalty and devotion amidst surrounding pagan cultures.

The prohibition of worshiping other gods signifies a powerful declaration of identity for the Israelites. It's reminiscent of a series of strong "House Rules" that serve to shape a community's understanding and relationship with the divine. The first commandment, located in Exodus 20:3, established monotheism at the heart of Israel's beliefs — a belief in one sovereign creator, distinct from the many deities in neighboring cultures.

What’s fascinating is how throughout the narratives, this verse echoes. In Deuteronomy 6:14, Israel is reminded not to pursue other deities, which reflects the surrounding risks of cultural assimilation. The children of Israel faced not just a theological challenge, but a social and cultural one while in a land teeming with idol-worshipping practices.

There's an interesting repurposing in the story of the Prodigal Son (Luke 15:11-32). In a way, turning towards 'other gods' can symbolically represent straying from one’s values or homeland, which brings about a yearning for home — very much in line with why these first commandments served as family rules to keep one anchored in faith.

In a larger biblical context, the recurring theme is this call for fidelity, challenging believers to evaluate what ‘idols’ might be lurking in their lives today — promoting a genuine discussion on what's worth our devotion in modern culture. Rediscovering this original call to loyalty invites contemplation on our relationships, choices, and commitments.