During the fateful military campaign that would ultimately claim King Saul's life, David faces a severe conflict of loyalty. Having found refuge among the Philistines, he marches alongside their army toward a battle against Israel. He is caught between his duty to his hosts and a deep reluctance to fight his own people, despite Saul's relentless pursuit of him [רש״י, ביאור שטיינזלץ]. Ultimately, David and his men do not assist the Philistines in their war against Israel [רש״י, מצודת דוד]. The Philistine commanders hold a deliberate consultation and decide to dismiss David from the front lines, sending him back to his home in Ziklag [רש״י, מצודת דוד, רלב״ג]. Their decision stems from a deep lack of trust. The commanders fear David has joined the campaign with deceitful intentions, worrying that he might betray them in the heat of battle. They suspect he plans to cut off their heads and present them to Saul, hoping to appease his master and earn forgiveness for his rebellion [מצודת דוד, ביאור שטיינזלץ].
Against this backdrop of rejection and shifting alliances, a group of warriors from the tribe of Manasseh approach David and align themselves with him to offer their help [רש״י, מצודת ציון, מלבי״ם, ביאור שטיינזלץ]. Commentators offer different perspectives on the exact timing of this new alliance. One approach suggests the encounter takes place while David is traveling back to Ziklag after his dismissal by the Philistines. The warriors from Manasseh are originally on their way to assist Saul in his battle against the Philistines, but upon crossing paths with David, they change their course and choose to join him instead [מלבי״ם]. Another perspective connects their arrival to the tragedy waiting for David at home. When David returns to Ziklag, he discovers the city burned and the families taken captive. According to this view, the warriors from Manasseh join him at this critical moment, helping him pursue the raiding party until they successfully rescue the captives and recover a massive amount of spoils [רלב״ג].