Exodus 40:34-38

Then the cloud covered the Meeting Tent, and the glory of the LORD filled the Holy Tent. Moses could not enter the Meeting Tent, because the cloud had settled on it, and the glory of the LORD filled the Holy Tent. When the cloud rose from the Holy Tent, the Israelites would begin to travel, but as long as the cloud stayed on the Holy Tent, they did not travel. They stayed in that place until the cloud rose. So the cloud of the LORD was over the Holy Tent during the day, and there was a fire in the cloud at night. So all the Israelites could see the cloud while they traveled.