The collapse of Saul's royal house is ultimately brought about not by foreign armies, but through a painful internal betrayal. The deepest tragedy of the heir's downfall lies in the fact that the very men entrusted with his protection were the ones who orchestrated his murder.
Two brothers served as senior military commanders in charge of the royal troops [מצודת דוד, ביאור שטיינזלץ]. As high-ranking officers directly serving Saul's son [רש"י, מצודת ציון, רד"ק, אברבנאל], they enjoyed unrestricted access to the inner workings of the palace. This trusted position explains how they managed to enter the king's private bedchamber without raising any suspicion. The royal guards simply assumed the commanders had arrived to speak with the monarch [רד"ק].
However, the exact nature of their history with the royal house is a matter of debate. A more dramatic perspective suggests a pattern of violence, positing that these brothers were destroyers who had already murdered another of Saul's sons in the past. After fleeing to the city of Gittaim, they learned of the shifting political tides—specifically the death of the kingdom's top general and the resulting weakness of Saul's heir. Seizing the opportunity, they returned disguised as wheat merchants, intending to assassinate the king and win David's favor [רד"ק, אברבנאל]. A middle approach proposes that the brothers had indeed served the king previously, but a bitter dispute caused them to flee. They later returned under the false pretense of reconciliation and peace [רד"ק, אברבנאל].
The narrative deliberately highlights the brothers' origins in the city of Beeroth to deepen the sense of betrayal. Because Beeroth was situated near the border, its tribal affiliation was often unclear, making it necessary to clarify that the city belonged to the tribe of Benjamin [רד"ק]. This specific detail amplifies the tragic nature of the assassination: the murderers came from the king's own tribe. It reveals a monarch so vulnerable and isolated that he could not even rely on his own kinsmen for safety [מצודת דוד, רד"ק, מלבי"ם]. Alternatively, the focus on Beeroth might hint at a different background altogether. Since the city was originally a non-Israelite settlement before being absorbed into Benjamin's territory, the assassins themselves may have been of foreign descent [ביאור שטיינזלץ].