יהושע, פרק כ״ב, פסוק כ״ו

A deep fear of a future disconnection between the tribes led Reuben, Gad, and half of Manasseh to initiate a practical solution to preserve their bond with the Israelites. To fix this situation and remove any anxiety, they decided to take definitive action [מצודת דוד, מלבי״ם]. They resolved to create something for their own sake [ביאור שטיינזלץ], which would serve as a true and lasting sign that they too were children of the living God [מלבי״ם].

The action they chose was to build an altar, but one with a very specific limitation. It was never meant for burnt offerings or actual sacrifices. Instead, it was intentionally constructed purely for visual purposes. Building an altar that was not meant for actual religious service sent a clear message. It demonstrated their understanding that any altar standing outside the central Tabernacle is invalid for sacrifices, as the proper service of God must be performed exclusively before Him in His central Tabernacle. In this way, the structure was meant to serve as an eternal witness to their faith, preventing anyone in the future from claiming that these tribes had no portion in God [מלבי״ם].