And so it was, when the cloud abode from even unto the morning, and that the cloud was taken up in the morning, then they journeyed: whether it was by day or by night that the cloud was taken up, they journeyed. Whether - by day or by night - As the heat of the day is very severe in that same desert, the night season is sometimes chosen for the performance of a journey; though it is very likely that in the case of the Israelites this was seldom resorted to.
Related Commentaries of Numbers 9:21
Numbers 9:21
21 And so it was, when the cloud abode from even unto the morning, and that the cloud was taken up in the morning, then they journeyed: whether it was by day or by night that the cloud was taken up, they journeyed.