From Bob Schlenker

Joshua 3:3-5a (NASB)

A) 3 and they commanded the people, saying,

B) “When you see the ark of the covenant of the Lord your God with the Levitical priests carrying it, then you shall set out from your place and go after it.

C) 4 However, there shall be between you and it a distance of about 2,000 cubits by measure.

C’) Do not come near it,

B’) that you may know the way by which you shall go, for you have not passed this way before.”

A’) 5 Then Joshua said to the people …

The B) elements mark the cessation of the pillar of cloud by day and pillar of fire by night, by which they had known which way to go for 40 years in the wilderness. As they cross the Jordan into the promised land, they will now follow the Lord’s presence that is associated with the Ark of the Covenant.