תהלים, פרק ק״ה, פסוק ל״ט

As the Israelites departed Egypt and began their journey through the desert, God led and protected them using a pillar of cloud and a pillar of fire. Because the fire was specifically designated to provide light at night, the cloud operated during the day [אבן עזרא]. The primary approach among commentators is that this cloud functioned as a vast curtain, offering both shelter and guidance. When the people camped, it spread above them as a protective canopy to block the intense heat of the sun. When it was time to travel, it moved ahead to lead the way [רד״ק, מצודת ציון, מצודת דוד]. The cloud was large enough to envelop the camp from all sides, sheltering the Israelites from above while extending forward to guide them [מאירי, מלבי״ם].

Beyond offering relief from the desert climate, the cloud acted as a physical defense during the Egyptian pursuit. When the Israelites were gripped by fear of the approaching army, God shifted the pillar of cloud to the rear of the camp. In this position, it became a thick shield that absorbed the arrows and catapult stones launched by the Egyptians. This heavy screen also separated the two camps entirely, blocking any light from reaching the Egyptian forces and leaving them in complete darkness [אלשיך].

Once night fell, the pillar of fire took over. God provided this fire to banish the darkness of the desert, illuminating the surroundings and ensuring the Israelites could safely see their way forward [מצודת דוד, ביאור שטיינזלץ].