Numbers 9:20-21

20So it was, when the cloud was above the tabernacle a few days: according to the command of the Lord they would remain encamped, and according to the command of the Lord they would journey.

21So it was, when the cloud remained only from evening until morning: when the cloud was taken up in the morning, then they would journey; whether by day or by night, whenever the cloud was taken up, they would journey.