שמואל א, פרק י״ח, פסוק י״ז

A royal marriage proposal is revealed to be a deadly political trap, as the king wraps his intention to eliminate a rival in a cloak of kindness and closeness. Saul offers his older daughter to David, but a deeply dark motive hides behind the gesture.

The primary approach among commentators is that this offer fulfills the original promise Saul made to anyone who would defeat Goliath [ביאור שטיינזלץ]. By specifically offering his older daughter, Saul tries to make the gesture look like a special favor, since he could have technically given his younger daughter and forced David to wait [מלבי״ם]. On the other hand, a different perspective suggests that the original promise during the battle with Goliath was merely an unfounded rumor spread by the people or a royal exaggeration, as Saul had never actually discussed it with David. In this view, the current proposal is a completely new initiative designed to make the marriage seem like an enormous act of grace to which David has no real right [אברבנאל].

By presenting the marriage as a massive favor, Saul establishes a strict condition. He demands that David not merely hold the status of a son-in-law, but act as a loyal son and a warrior, going out to fight the battles of God [מלבי״ם, ביאור שטיינזלץ, אברבנאל].

In reality, Saul's outward words only mask the calculations in his heart [רש״י, ביאור שטיינזלץ]. The marriage offer does not stem from any affection for David [מצודת דוד]. Instead, it is a backup plot conceived after Saul failed in his direct attempt to strike David with a spear [אברבנאל]. Saul calculates that his own hand should not harm David, fearing the punishment that would follow if he committed the murder himself [רש״י]. Therefore, he plans to send David into constant warfare, ensuring that the Philistines will strike him. By keeping him on the battlefield, the enemy will do the deadly work for him, and David will fall in combat [רש״י, מצודת דוד, מלבי״ם].