דברי הימים א, פרק ט״ז, פסוק כ״א

The early forefathers lived a completely nomadic life, constantly wandering from place to place. As rootless strangers in foreign lands, they were highly vulnerable. Travelers and wayfarers are typically easy targets for harm and false accusations on the road or in places of lodging, yet God did not allow anyone to hurt them [רש״י, ביאור שטיינזלץ]. He ensured that no one could rob, deprive, or exploit them [מצודת ציון, ביאור שטיינזלץ].

One might assume the forefathers survived simply by keeping a low profile and going unnoticed by the local populations. However, God's protection was highly active and visible. He directly intervened to warn and punish those who noticed the forefathers and attempted to do them wrong, inflicting pain and exacting retribution for any evil intentions [מצודת דוד, מצודת ציון, ביאור שטיינזלץ].

The primary approach among commentators is that God actively afflicted powerful rulers to defend them. For instance, God struck both Pharaoh of Egypt and Abimelech of the Philistines with severe plagues when they took Sarah [רד״ק, רלב״ג, מצודת דוד]. This harsh divine response instilled a deep fear that later stopped Abimelech from harming Rebekah [מצודת דוד].

This shield of divine protection continued to follow the forefathers throughout their journeys. Even when Abimelech forced Isaac to leave his territory, he avoided exploiting him and ultimately felt compelled to make a peace treaty with him. In the same way, God guarded Jacob from the threats of Laban and the inhabitants of Shechem, issuing direct warnings to ensure they would not touch him [רש״י, רלב״ג].