במדבר, פרק כ״א, פסוק כ״ו

The Israelites' journey to the Promised Land involved military conquest, but they operated under strict divine boundaries. God explicitly forbade them from taking any territory belonging to Ammon and Moab. Yet, they successfully captured the region of Heshbon, an area that originally belonged to the Moabites. This apparent contradiction is resolved through a crucial piece of regional history.

The primary approach among commentators is that Moab had previously lost Heshbon in a war against Sihon, king of the Amorites. Once Sihon captured the region, its legal status changed. It was no longer considered Moabite territory; it became Amorite land. This shift cleared the way for the Israelites to conquer the area, as they were now taking it from Sihon rather than from Moab [רש״י, תורה תמימה, הכתב והקבלה, מלבי״ם, בכור שור, דעת זקנים, הדר זקנים, ביאור יש״ר]. This earlier conflict between the Amorites and Moabites was not a random historical event. Rather, it was a deliberate plan directed by God specifically to extract the land from Moabite control so that it could eventually be given to the Israelites [משכיל לדוד].

Sihon did more than just capture the territory. He transformed the city's identity, establishing it as his royal capital. This decisive action caused the Moabites to abandon any hope of ever reclaiming their land [שפתי כהן, ביאור שטיינזלץ]. Commentators differ slightly on the timeline of Heshbon's rise to prominence. Some suggest it was already Sihon's capital before he launched his campaign against Moab [ספורנו]. Others maintain that Sihon first destroyed the existing Moabite city, rebuilt it, and only then declared it his seat of power [רמב״ן].

Sihon fought against the first king of Moab. This is widely understood to mean the king who ruled immediately before Balak, the monarch in power when the Israelites arrived [רמב״ן, הטור הארוך, דעת זקנים, הדר זקנים]. Another perspective suggests it simply refers to whoever ruled Heshbon prior to Sihon's takeover [רש ר הירש]. A more unique historical angle proposes that this was literally the first king the Moabite nation ever appointed. According to this view, the Moabite people strongly opposed the idea of a monarchy. In their rebellion, they actually invited Sihon to overthrow their newly crowned leader. Sihon seized the opportunity, defeated the king, and claimed Heshbon for himself [העמק דבר]. Sihon's seizure of the land from the king's hand refers to stripping away his legal authority and control, rather than a literal physical grasp [רש״י, תורה תמימה].

The extent of Sihon's conquest reached the Arnon. There is some debate regarding this boundary. Sihon either captured the entire territory including the river itself [רמב״ן], or he took the land right up to the riverbank, leaving the watercourse as an unconquered natural border [רלב״ג].