A profound shift occurs as a tortured king finally confronts the reality of his successor. Saul’s sudden recognition of David’s destiny stems from a troubled conscience, sparking a sobering new perspective on his situation. He acknowledges with absolute certainty that David will eventually take the throne. The primary approach among commentators is that Saul can no longer ignore the obvious: God repeatedly rescues David from his grasp and blesses David's path with success.
Beyond simply witnessing David's survival, Saul recognizes the deep moral strength required to lead. By conquering his own impulses and choosing not to harm the king when he had the chance, David proves that true leadership belongs to the one who can master his own spirit [מלבי״ם]. Additionally, Saul may have already been aware of the rumors that Samuel had secretly anointed David [רד״ק]. A deeper layer of understanding is found in a well-known tradition cited by most commentators. It suggests that Samuel had previously given Saul a specific sign: the man who tears the corner of Saul's robe is the one destined to replace him. Confronted with the physical evidence that David had done exactly that, Saul instantly understands that the prophecy is unfolding before his eyes.
The specific manner in which Saul speaks of David's future rule hints at a gradual rise to power. The kingdom will not be united under David all at once; rather, the process will happen in two distinct stages. He will first rule over the tribe of Judah alone, and only later will his authority expand to encompass all of Israel [חומת אנך]. Saul also recognizes the enduring nature of David's future reign, declaring that the kingdom will achieve lasting stability and survive the test of time [מצודת ציון]. This permanent establishment of power will be the direct result of David's good deeds and natural capabilities [מצודת דוד].
For Saul, this admission is a painful moment of comparison between himself and his rival. He is forced to accept that the royal power which slipped through his own fingers will find permanent stability in David's hands [מלבי״ם, רד״ק]. This bitter realization directly echoes the harsh judgment Samuel delivered after the war with Amalek, when the prophet informed Saul that God had torn the kingdom away from him to give it to a better man.