מלכים א, פרק ט״ז, פסוק י״ט

Zimri faces severe punishment for a legacy of sin and for leading the nation astray, yet his time on the throne lasted a mere seven days. This brief rule raises an obvious question about how a leader could possibly commit such deep wrongs and corrupt the people in just one week.

The primary approach among commentators is that his record of wrongdoing stretches back long before he seized the crown. During his earlier career as a military officer in charge of half the chariots, he was already engaging in corrupt acts and leading the soldiers under his command down a sinful path. His guilt did not accumulate over seven days, but rather over a prolonged period of negative influence prior to his kingship.

As for his actual time as king, [מלבי״ם] explains that Zimri had fully resolved to maintain this corrupt trajectory. Even though his reign was cut short, his intentions were clearly set on doing evil. Furthermore, [ביאור שטיינזלץ] points out that beyond the act of rebellion itself, Zimri showed absolutely no desire to abandon the destructive legacy of Jeroboam during his short time in power.