The first two kings of the Jewish People in the Land of Israel were both plagued by actions so severe that they brought censure by God and His prophets. In King Saul’s case (see I Shmuel, chapter 15), the war against Amalek – where he allowed King Agag to live and did not destroy the animals of the Amalek nation, as commanded – led to Shmu’el’s rebuke, Saul’s admission of fault (see ibid:24), and the loss of his kingdom. In the case of his successor, King David (see 2 Shmuel, chapter 11), the incident with Bat-Sheva leads to Natan’s parable of the rich man who steals a poor man’s sheep, David’s admission of fault (see ibid 12:13) and a series of family tragedies.
Our Gemara examines the song sung by King David once he had established himself as king – “on the day that God saved him from the hands of all his enemies and from the hand of Saul” (see I Shmuel 22:1), commenting that God was unhappy with David’s portrayal of Saul’s downfall – “…had you been Saul and he been David, many David’s would have been destroyed before him.”
This enigmatic statement is understood by Rashi to mean that King Saul was seen by God as a more righteous individual than David, however it was not his destiny to remain king. Rabbeinu Gershom suggests that the intention is to say that had David possessed the qualities of modesty that were a basic part of Saul’s personality it would have been enough to make David deserve to be king.
Several reasons are suggested in an attempt to explain why it was not Saul’s destiny to rule over the long-term. The Iyyun Ya’akov suggests that the tribe of Yehuda had been chosen for leadership and not the tribe of Binyamin, so Saul’s monarchy was doomed from the first. The Ran and the Tosafot Ha-Rosh both suggest that it was Saul’s pristine family background that made him ineligible for long-term rule. Specifically because of the questions that existed in David’s background (descending from Ruth the Moabite), he was the appropriate model of a leader who could overcome adversity to rule.