וְאִם־לֹ֥א יֵעָלֶ֖ה הֶעָנָ֑ן וְלֹ֣א יִסְע֔וּ עַד־י֖וֹם הֵעָלֹתֽוֹ׃
But if the cloud was not taken up, then they journeyed not till the day that it was taken up.
Read kabbalistic (mystical) interpretation of Exodus 40:37: and classical mystical sources.