מלכים א, פרק י״ב, פסוק כ״ו

Despite a successful rebellion, being crowned by the masses, and completing significant building projects, Jeroboam experiences deep anxiety about the stability of his rule [ביאור שטיינזלץ]. He is terrified that his grip on the kingdom will slip away rapidly and in the very near future [מצודת דוד].

This intense fear stems from the religious obligation of the people to travel to Jerusalem for the three pilgrimage festivals [מלבי״ם, אברבנאל]. Jeroboam realizes that allowing the people to visit the House of God and offer sacrifices there will set off a dangerous, gradual chain of events that will ultimately strip him of his crown.

First, the journey to Jerusalem will cause the people to return and reconcile with Rehoboam, whom they view as their true and natural lord. Second, fueled by this renewed loyalty to the House of David, the masses will conspire against Jeroboam and assassinate him. Finally, following his death, the entire kingdom will officially and openly return to Rehoboam's control.