Life is a constant cycle of departures and returns, requiring a promise of absolute and comprehensive protection over all human movement. The primary approach among commentators is that God watches over a person physically whenever they step out of their home and when they return, shielding them from obstacles throughout all their travels [ביאור שטיינזלץ, מצודת דוד]. On a more specific level, this is a promise of special protection during times of conflict, ensuring that a person who goes out to war will return in peace [אבן עזרא, מאירי].
The nature of this divine protection directly reverses standard human practice. A mortal king sits safely inside his palace while his servants stand guard outside. In contrast, God places His servants securely inside their homes while He Himself stands guard on the outside, an idea reflected in the commandment to place a sacred sign on the doorpost [תורה תמימה].
There is a distinct sequence in these movements, prioritizing the departure over the return. This contrasts with the blessing of Moses, who placed the arrival before the departure. One reason for this order is that a person faces the most danger when leaving the safety of a city to go on a journey, making the need for protection greatest at that moment. Yet, God promises to maintain that same careful watch even when the traveler returns to the relative safety of the city [מלבי״ם]. From a historical perspective, Moses spoke to the Israelites before they entered their land, so he mentioned arriving before the eventual departure into exile. David, however, looked ahead to the period of exile. Therefore, he spoke first of leaving the exile, followed by the return to the Land of Israel—a return that will be continuous and permanent [מאירי].
Beyond physical travel, this cycle of movement reflects the deeper journey of the soul, representing birth and death. Just as a person comes into the world entirely free of sin—since the urge to do wrong only enters at birth and not in the womb—God promises that a person's departure from this world can be equally pure [חנוכת התורה]. The departure also points to the soul leaving the physical world, with a promise that God will shield the individual from the pain of death and the fear of what lies beyond. The return then hints at the soul coming back in future lifetimes, during which God will grant the person a pure spirit to help them avoid repeating past mistakes. Alternatively, the departure refers to passing away from this world, while the return points forward to the ultimate arrival of the Messiah [אלשיך].
Ultimately, this divine watchfulness is not limited by time. It encompasses every moment without exception [מלבי״ם], promising to accompany a person not only through all the days of their life but continuing endlessly into eternity [אלשיך, מאירי].