Solomon’s confrontation with Abiathar the High Priest marks a decisive moment in securing his kingdom and dismantling the remnants of Adonijah’s rebellion. Solomon realizes that Adonijah’s recent request to marry Abishag was not conceived in isolation. Rather, it is part of an ongoing political plot orchestrated by his advisors, prominently including Abiathar [ביאור שטיינזלץ]. As long as Solomon tolerated Adonijah’s initial actions, he held back from punishing his advisors. However, once the conspiracy is renewed, the king decides to deal with the conspirators directly [אברבנאל].
Taking decisive action, Solomon strips Abiathar of his position as High Priest and banishes him from the royal court [אברבנאל, ביאור שטיינזלץ]. He orders Abiathar to return to Anathoth. The primary approach among commentators is that Anathoth was a recognized city of priests and Abiathar’s personal home. Because priests did not inherit agricultural farmland, the properties he is sent back to likely consisted of open pasturelands designated for their flocks [אברבנאל] or simply a private residential estate within the city [רלב״ג].
Solomon makes it clear that Abiathar is guilty of treason and legally deserves the death penalty. The primary approach among commentators is that his rebellion consisted of allying with Adonijah and attempting to crown him while David was still alive. He did this behind David's back, fully aware that the aging king intended for Solomon to inherit the throne [רש״י, רד״ק]. Furthermore, his current involvement in the request regarding Abishag proves that he still harbors a rebellious spirit and continues to advise against the reigning king [מצודת דוד, אברבנאל].
Despite this clear guilt, Solomon spares his life. He emphasizes that even though the spirit of rebellion is still evident in Abiathar at this very moment, he will be saved from execution [מצודת דוד]. Another significant motive for avoiding the execution of the High Priest is Solomon's desire not to repeat the terrible sin of King Saul, who notoriously slaughtered the priests of God in the city of Nob [אברבנאל].
Ultimately, Abiathar’s life is spared due to his past loyalty and the kindness he showed to David during times of great distress. First, he faithfully carried the Ark of the Covenant when David was forced to flee from his son Absalom, keeping it with him until David ordered its return to Jerusalem. Second, Abiathar fully shared in David’s suffering, enduring hunger and exhaustion on the road [רש״י, רד״ק, מצודת ציון]. While some trace this shared hardship specifically to the flight from Absalom [רש״י], others point to the days when Saul hunted David [מצודת דוד]. A combined perspective notes that ever since Saul massacred the priests of Nob, Abiathar never left David’s side. He suffered through all his troubles, consulted God for him, and sought to join him when fleeing Absalom [רלב״ג, אברבנאל]. Finally, a unique angle suggests that Solomon shows mercy because David himself was the indirect cause of the massacre of Abiathar’s family in Nob. Therefore, it would be deeply improper for David’s household to bring harm upon him yet again [חומת אנך].