Joshua 3:2-4

2Now it came about after three days that the officials went through the camp

3and they charged the people saying, “When you see the ark of the covenant of Adonai your God and the Levitical kohanim carrying it, then you must set out from your place and follow it.

4Yet keep a distance between you and it of about 2,000 cubits by measure. Don’t come near it, so you may know the way by which you should go, for you haven’t travelled this way before.”